Okay, okay -- Grant A. Tinker, chairman and chief executive officer of NBC, will put his shoes on for the interview, though he'd clearly prefer not to. They're brown loafers -- not Guccis -- and he is wearing them with white socks, jeans and a boppy blue sweater. "I have a problem feeling chairmanlike, in the way you're supposed to," he says.

Obviously, Tinkering is schlepping around his Burbank, Calif., office, not his Rockefeller Center office. In New York he wears A Suit And Tie, those dowdy remnants of a previous, East-coastal U.S.A. "Yeah, I would be locked up, literally locked up, if I were to walk into RCA in anything less than a suit. I mean, those guys are very, very buttoned up!"

Grant A. Tinker, who turned 56 last month, is very, very open-collared -- tanned, fit, sensitive about the angle at which he is photographed -- a cool yet commanding character, an unlikely messiah to heal a crippled company perhaps, but one whom leaders throughout the industry revere. This man is so respected in broadcasting, he's like Abraham Lincoln, but it's not clear at this point whether NBC, like the Union, can long endure. After six months of the Tinker regime, there is no dramatic evidence yet of a turnaround, no striking impression of a Tinker-tailored NBC.

Near the windows in his modest Burbank office, beyond the coffee table with the bowl of walnuts on it, sit a high desk and chair, like an architect might use, which Tinker needs for a problem back and which he brought over from his previous hangout, MTM Enterprises, the company named after ex-wife Mary Tyler Moore, where he spent 11 years as president, inspiring writers and producers to do their best for television.

Tinker looks over at the desk. "I invented it; I had it built for my MTM office," he says, and then, with a smiling sigh, "God, I wish I was still there -- but that's another story."

Later he mumbles, as a flippant aside, "I gotta get outta this job," but he's joking. Really. Just kidding around.

He's a sly kidder, and a shy boots -- so shy that an NBC publicist jumps in when questions seem too personal. Tinker is not asked about his marriage to Moore, nor other aspects of his personal life. He is guarded about himself, open about his business. "He's the first chairman ever to eat in the commissary," crows the publicist. "Yeah, sometimes I fly in just to eat lunch," Tinker jokes. "No, no, I don't see that as such a big deal, to tell you the truth," though at least one old-line NBC executive was irked to find that a lunch invitation from Tinker meant a hasty nosh in the company cafeteria.

There are those, however, who say NBC needs a lot more right now than Mr. Nice Guy, a Longfellow Deeds of broadcasting.

Tinker admits he underestimated the number of NBC problems he would inherit when he took over from Fred Silverman last July; the magnitude of Silverman's failure and the crotchety intransigence of the NBC bureaucracy, are only now becoming clear to him, though he is enough of a gentleman -- in the context of network television, virtually a saint -- never to say anything derogatory about Silverman's record. Besides, NBC's problems go beyond the three-year reign of terror presided over by formerly fabulous Freddie.

RCA, which owns NBC, recently announced an enormous 83 percent drop in earnings for last year -- $54 million in 1981 vs. $315.3 million for 1980, with NBC's low ratings blamed for some of the loss. This provoked rumors that RCA might even put the peacock on the block, were there a buyer, but it is more likely the company will divest itself of such nonbroadcast properties as Hertz Rent A Car.

Recently trade publications revealed that NBC has stopped selling ad time for the first quarter of this year, one reason being the network has to air so many "make-goods" from the fourth quarter of last year. A network airs make-goods, in essence free ads, when it has failed to deliver to advertisers the ratings it predicted shows would get. Ratings are down for "The Tonight Show" and the "Today" show; NBC's daytime schedule is a horrendous disaster. Not since ABC's doormat days in the '50s has a network been in such a depressed condition; one waggish Hollywood writer says NBC is not just in third place, but in fourth -- "right after CBS, ABC, and Atari."

"I had an outsider's idea of the problems," says Tinker. "I didn't know how difficult they would be to solve. And I'm finding some of that out as I go along." Tinker, unlike his precedessor, has steadfastly refused to publicly set deadlines for improvement at NBC, but when pressed, he does say, "If in a couple of years, we are exactly where we are now, I would not feel like we're succeeding. In fact, I would feel like something of a failure. Not that we'll have done it all in two years, but I would like -- in fact, I confidently expect -- there will be very evident signs of upward progress."

It's hardly bravado. It's hardly pugnacity. But those are not Tinker qualities. Tinker qualities are more in the tenacious-sagacious area. Hollywood producers sent up a rocket when he was appointed by RCA chairman Thornton Bradshaw; here was a man who understood their problems and their grievances against network airheads and numbskulls. Even though he has crossed over now to the other side, Tinker, asked about the abysmally low quality level of television generally, says, "I think the blame can be laid with us. In terms of product, I'm sure we'd agree there hasn't been a lot that's different or new or better.

"I don't think we're bereft creatively, but I don't think we should be winning any awards right now, as a business. I think we're just doing more of the same old stuff." How long until that changes? "I don't know." Is he the one who will do the changing? "Well, I wouldn't go quite that far. But I'm one who would love to see it change." Crisis of Confidence -------

Tinker's challenge goes further than giving repeated Heimlich maneuvers to a choking and gasping NBC. Television is going through a tremendous crisis of confidence, a loss of faith. The network share of the total viewing audience fell to another new low last year, as viewers were siphoned off by cable, pay TV, independent stations, Space Invaders, whatever. Shows that ratings put in the hit column this year have nevertheless made little impact on the public mind; they're not talked about. They're watched begrudgingly, not eagerly.

It's as if people on both sides of the tube have stopped believing in television, or have at least stopped believing in its capacity to improve.

"I would like to see some more 'Hill Streets,' " says Tinker, referring to NBC's one cutting-edge smash, "Hill Street Blues," one of the last programs created at MTM before he left. "I would like the mix to be better. I just think on all three networks the stuff too often is witless and forgettable . . .

"It's chicken-and-egg in the worst, negative sense. As we just do more of the same old stuff -- I'm using 'we' in the three-networks sense -- the audience gets a little more disenchanted all the time, or a little less interested, or is a little more able to be distracted by cable or whatever, and they drift away. And then they're harder and harder to get back even when you do good stuff."

Alternative TV tends to get its audience from so-called "upscale," higher-educated viewers, which will eventually leave the networks, some insiders think, with only the "P&G crowd," the blue-collar audience to whom Procter & Gamble and similar companies pitch soap and toilet paper. "I hope the way to compete is not only to do that lowest common denominator thing with a lot of sizzle," says Tinker. "Because if that's true, it's going to get less and less interesting to work in the medium."

Tinker may not seem on the surface to have a lot of "sizzle" himself, but that's only because he's a quiet sizzler. He doesn't want to make a lot of noise rebuilding NBC, but he is determined to do it. James L. Brooks, the brilliant MTM writer-producer now at Paramount making movies ("Starting Over") and TV shows ("Taxi"), when asked about Tinker outside Ma Maison, said simply, "The company, the company." Tinker is not so much a company man as a man-company. No, he won't become hysterical if he can't save NBC, he says -- he does not have a flamboyant temperament -- but, he promises, "I will get very, very depressed."

How will he work the old miracle? Partly by attracting the kind of talent he attracted to MTM, although he says that when it comes to making a hit series, and a good series, "the problem is, there aren't that many creative people that can do it." He also wants to make NBC a less panic-stricken organization -- "if people are a little happier about coming to work, it can't hurt" -- and stay away from "what is reputed to be the black-tower climate of Universal, where everybody is cowering on the stage and somebody is yelling, 'We're going to pull the plug at 7 o'clock if you don't get this thing done.' "

He doesn't appear now to have any revolutionary ideas about how to save network television, but he is more likely than any other executive at any other network to find the people who do have the revolutionary ideas. And one funny thing: As lowly and pitiful as NBC's competitive situation is, almost all the shows worth talking about in television -- "Hill Street," "Fame," David Letterman, Johnny Carson, "SCTV" -- are on NBC. Silverman, it should be noted, had something to do with that.

When he talks about "a more eclectic schedule" and raising the taste level of television, however, Tinker is essentially repudiating everything Silverman stood for: going after the kiddie crowd, blitzing the audience with cheap gimmicks, scrambling frantically for ratings at any cost. On the record, however, Tinker will not say anything against Silverman; he personally vetoed a tasteless and unfunny "Saturday Night Live" sketch attacking Silverman because he thought that would be "a tacky thing to do." He maintains that part of Silverman's affliction was sheer bad luck ("he was snake-bit") and another part the fact that Silverman became a bigger show than his shows. Tinker is determined to keep a profile as shadowy as The Thin Man's and stay away from the kind of hubbub that surrounded The Fat Man.

"Our business should be like any other business," he says. "I see no reason for me to be any more visible than the guy running a lumberyard." But the guy running a lumberyard isn't affecting America's manners and morals. "But I don't understand why that person who is affecting America's manners and morals has to be that visible. He can be responsible and he has to be willing to accept the credit or blame or what-have-you, but I don't know why he has to be up there in that public view all the time . . .

"I think that was another thing that happened to Fred, that the media attention just got bigger than the show." Still, he appreciates a good Silverman anecdote as much as the next guy. When Silverman left NBC for MGM, just as he'd done when he left ABC for NBC, he went out to buy an expensive new wardrobe; when he showed up, later, at NBC one day and Tinker was trying to make "small talk" with him, Silverman said he couldn't wear any of his new clothes because he'd lost so much weight.

"And I'm looking at him," Tinker recalls, "and he hasn't lost a pound! If anything, he looked bigger to me than he used to."

At that meeting, Tinker says, "I was saying things like, 'Fred, you look so relaxed,' which he did, and I was feeling not relaxed at all. I wanted to say, 'You sonofabitch! How could you leave this place? It's a shambles!' " He laughs.

Tinker has had his own crises at NBC already. He intervened in the delicate matter of Gary Coleman, the bossy tot having an attack of contractitis on NBC's "Diff'rent Strokes." Tandem Productions, which makes the show, wanted to continue without Coleman rather than cave in to all his agent's demands. Tinker's response, an insider says, was to tell Tandem chief Alan Horn that they could continue without Coleman if they wanted to, but that they'd have to find a diff'rent network for "Diff'rent Strokes" if they did. Coleman returned.

More substantial and less successful was the loss of David Brinkley, a 38-year NBC News veteran, to ABC. Common industry scuttlebutt (denied by Brinkley, but not forcefully) was that Brinkley left after a series of tiffs with NBC News president William J. Small, and that Tinker refrained from firing Small over this debacle only because he wanted to preserve the illusion of stability at NBC so soon after his takeover.

"I am interested in stability, but that isn't the case," says Tinker. "Bill Small is a damn good professional head of news. There's no question. In truth, he is two things; he's that stand-up comic we saw with the affiliates at a recent meeting who love him because he is a pro. But I guess he's a hard guy to work for, he's just kind of an autocratic guy I guess, or at least he seems that way, and doesn't go out of his way to stroke everybody."

The exits of Tom Snyder and Rona Barrett do not trouble him as much. It is indicative of Tinker's admirable candor that at a Burbank press conference, when NBC publicists wanted to waffle and fudge on the subject of Barrett's and Snyder's status with the network, Tinker said, "Let's not dance too much here" and, "Rona is no longer with us; that is also true of Tom Snyder." Questions of Firepower -----

In the presence of Silverman, one often felt entertained, bedazzled, sometimes bamboozled, always amused. With Tinker, you feel reassured, bolstered, fine-tuned. The one misgiving about Tinker repeatedly voiced within the business is that he may lack "the fire" to get NBC moving, that he is just too darn mellow. Tinker won't say what secret smasheroos he may have waiting in the wings; a few big hits would mean a lot to NBC. He does say things like, "I'd like to have the Ed Sullivan show" back, with a new Ed "if we could find him. I'm not sure we can. Wouldn't you just love to have the Ed Sullivan show? That occurred to me this morning. You know who could do it?Carson could do it. He could do it like that, because he's in touch with the audience as Sullivan strangely was."

Tinker's ex-wife, of course, flopped big on CBS a few years ago with an attempt to do a musical-variety show, which did not bode well for the format. "I think Mary's judgment was questionable there," says Tinker. "I'm sure she'd admit that, too. I did not work hard enough to dissuade her. So we both can be blamed."

In an interview while still MTM president, Tinker once said that if Carson pulled another temper tantrum about wanting to leave, "I'd say, 'okay' " because it is becoming "unaffordable to keep him, and I would just plop David Letterman right down in that chair." Reminded of the remark now, he says, "Yeah, that was probably unnecessary. I'm not looking for opportunities to repeat it."

In that same interview, Tinker sounded droopily morose about the prospects for network television. He said its decline and fall, and the sorry state of programming, "comes close to a national scandal. Somebody ought to go to jail for that." Who? Network executives? "Yeah, probably. It's certainly not the producers, because we only sell what they'll buy."

"I probably said all those things," Tinker concedes now. "It goes back to what we were talking about; not enough of TV is aimed high enough, and wherever it's aimed, not enough of its targets are hit. I think I'm as offended by the failure to hit those targets as I am by the level of the targets. I also think some of the distractions, like the Moral Majority kind of thing, are beside the point almost. I mean, the point is, we don't do it well enough. It's not, is it too sexy, or too violent, or too whatever, if it's not good enough.

"I obviously feel more bullish about it now, because the mountain is here, and you gotta climb it. We have plenty of work to do and a difficult situation in which to do it, because it is a business of momentum, and we don't have much."

On this day, when a visitor arrived to meet with Tinker in Burbank, and was signing in with the security guard, he looked down at the desk to see a crumpled guest pass that had recently been turned in. The name on the pass was "F. Silverman." Yes, it was Freddie. He had been there that very day pitching one of his shows. Grant A. Tinker knows that in two years, the name on the guest pass could be his; his reputation is on the line, NBC is on the line, and for all anybody knows, network television is on the line, too.