It is still 1960 in the Baltimore of Barry Levinson's "Diner," the pilot for a TV series based on the evocative, warmhearted movie about aging boys who don't want to grow up. The show airs tonight at 8:30 on Channel 9, and if it were just a little bit better, it would be almost as good as the film, which for TV is not a bad showing at all.

Levinson wrote and directed the pilot as he did the film. Again one is time-warped back to a day of relative innocence and the more or less random misadventures of a group of stalwart buddies who convene regularly at a beloved greasy spoon.

The only member of the film cast to appear in the pilot is Paul Reiser as Modell; otherwise, the gang consists of James Spader (a very busy young actor, currently on NBC's "Family Tree") as Fenwick, Mike Binder as Eddie, Max Cantor as Shrevie, and Michael Madsen as Boogie.

Two of the women in their lives are endearingly, tough-tenderly played by Mady Kaplan as Shrevie's wife, and Alison LaPlaca as Eddie's new bride, the one who had to pass the football trivia test in order to make it over the threshold. The men talk about women, the women talk about men, but in the pilot the women talk much more engrossingly.

"Diner" is beautifully produced--with no laugh track, bravely enough--and is scrupulously well-acted, but its chances of success as a weekly series seem slim. The viewing public is conditioned to accept the artificial "Happy Days" version of the era depicted in "Diner," not anything even remotely realistic. Also, a melancholy cloud hangs over the program. One could leave the movie imagining whatever futures for the characters one wanted, but with the TV series, we would find them essentially stranded in a tacky adolescence week after week.

There are other discomforting things about the world these characters inhabit--one is that it's lily-white, the other that its depictions of how male-female relationships were conducted in the old days seems too uncritical, even sentimental, as if we'd all be better off going back to them. Perhaps the original "Diner" is a memory best left undisturbed. 'PM Magazine'

Mediocre local programming may, in principle, be preferable to mediocre national programming, but about the most effusive praise one can muster for Channel 5's revamped "PM Magazine" show, premiering at 8 tonight, is that it is screamingly standard. The new nightly half-hour doesn't seem noticeably superior to the old "PM Magazine" so callously scrubbed several months ago by Channel 9, which then gave its 7:30 time slot to impossibly garbagey syndicated tripe such as "Lie Detector" and "Sha Na Na."

The new "PM" cohosts are the pleasantly dull Marcia Brazda and Joel Loy, though on the first program you don't get a very good look at them; they're off on some big boat. As before, the menu is a selection of soft-newsy features, some locally produced and others garnered from "PM Magazine" stations elsewhere in the country.

Now divided into segments such as "People," "Entertainment" and "Adventure," the program opens tonight with a poorly produced report on Michael Evans, Ronald Reagan's White House photographer. The least to be expected from such an undertaking is a good look at some of Evans' work, but the photos fly by quickly while the narrator, or extracts from an interview with the mumbling Evans, rattle on. Couldn't it have occured to the producer to ditch the talk for 90 seconds or so and just show the pictures Evans takes?

The segment also includes yet another telecast of a slow-motion replay of the shooting of the president in March 1982.

A segment on "Entertainment" is a witless plug for the Universal Tour in Hollywood; it concludes with Bruce the mechanical shark getting a pie in the face, the one nice touch on the show. "Adventure" tells of men and women who jump off tall buildings and bridges because, one of them says, "I really like scaring myself," and this is the show's most visual segment, though chatter still dominates.

An "Inside Guide" finds Redskins offensive lineman George Starke personably conducting a tour of the Redskins' summer camp in Carlisle, Pa., but we're given only a sketchy, flimsy impression of how the presence of the team affects the town. "People here make you feel really special," Starke says. That tells us a lot.

With the addition of the nightly "PM Magazine," WTTG boasts that it now does more local programming than any other station in town, not so mean a feat in this town, but commendable just the same. It has to be remembered, however, that for years and years WTTG has been nothing but a money-printing machine for Metromedia, the station group that owns it; it has a lot of contributing to do to make up for a general, nagging, lazy kind of lousiness. "PM Magazine" is only an itsy-bitsy baby-step in the right direction.