First she introduced NBC correspondent Bob Bazell as "Bob GaBozell." Then there was this problem with the cues. "Hello? Hello?" she called after a moving camera lens and 5.5 million viewers who saw her sideways instead of frontways. And pretty soon came a nervous young woman she was about to interview live. "Listen," she told the interviewee maybe 17 seconds to air time, "I'm malaproping all over the place. You're going to have to pull me through."

A little later one of the "Today" show set people came wandering over, saying maybe a pin or something would brigten her white dress for television.

"Why don't you," she suggested, "just put a scarf over my whole head?"

Mariette Hartley, the saucy blond you probably think is Mrs. James Garner from her Polaroid commercials, is filling in for Jane Pauley for three weeks.But just three weeks, those in the NBC news stratosphere emphasize nonetheless saying that Hartley, however green, is still spunky, irreverent, pleasantly refreshing. "In the parlance of the day," remarks "Today" show host Tom Brokaw, "she's a hot television personality."

And compared to the precision-cool Pauley . . . very different.

So they're looking Hartley over, maybe for "Today," maybe for "Tomorrow," maybe for an upcoming 11:30 a.m. news show for women. But something.

"I'm not sure whether she's interested," says NBC Vice President Richard Salant, "but I know I am."

"Look," says Steve Friedman, "Today's" executive producer, "they're very worried about the show. It's been No. 1 forever, and it's not any more . . . they're drowning, this network. They're having lots of problems." Among them: ABC's "Good Morning America" has pulled ahead of the 28-year-old "Today" show in ratings. And television critics are always saying that Pauley and Brokaw can't stand each other, although Brokaw routinely denies this.

But now Pauley, 30, the sorority girl from Indiana who was bred on TV journalism, is off on her honeymoon with cartoonist Gary Trudeau. And so here's Mariette Hartley, the career actress who did Shakespeare for Joseph Papp and is cast opposite Alan Arkin in "Proper Channels," a movie to be released this fall. She was 40 last Friday.

"Scares the hell out of me," she says. "Here I am, doing a three-week stint on the 'Today' show. Is this" -- she begins to sing, lustily -- "all there is?"

This is at 5:45 a.m. in the "Today" show's makeup room where they ask "Black or regular?" before they say "Good morning." But Hartley is singing chortling and providing the only available entertainment -- in her bathrobe.

"She's always like this," says the makeup lady.

"Do you remember," says Hartley, "the first time I read 'Morning Line' on the show?" The makeup lady and a few others standing around do seem to remember, but Hartley gets up anyway and grabs an imaginary machine gun from the air. "This is the way it sounded:

"Dadadadadadadadadadadada!" She's crouching, shooting a spray of ammo into the makeup mirror, the makeup lady, the hairdresser, an innocent reporter. "And the look on Tom's face," she laughs, "was, 'Gee, maybe you could take a breath between sentences."'

She settles back in the chair, and the hairdresser continues with the electric curlers. Hartley's hair is thin and wispy, her eyelashes short and pale, and there are lines around her mouth. Pre-makeup, she looks 40. Still, she has the fresh-faced, all-American look of a woman who plays tennis or drives the carpool or takes the kids to Little League practice. "Non-threatning", says Ethel Winant, a vice president at NBC who knows her well. "Women seem to relate to her, and men like her."

The hairdresser continues his work, dosing her head liberally with Kindness spray. She reads the script of the soft-news "Morning Line" and looks at her orange fingernails.

"Oh, I know what I need," she says. "A little bit of nail polish. I hate this color." She gets pink and sets aside her script, concentrating on an index finger.

Now that she's quiet, it seems a good time for the question everyone's been asking her, which is: How would you like to do the "Today" show for not weeks but years?

"Uhhhhhh," she begins, "s---." This is directed toward her fingernail "Well," she picks up, "I don't even think that was particularly the plan -- although I may be wrong." She thinks some. "I enjoy live television a lot, but I'm not crazy about the hours. And it's not just the hours. I have research, I have little trips to make during the day, I have books to read, I have theater to go to at night. I'm not used to that. I don't have to work this hard at home. I've thrown my family into such a frenzy -- and I also had no idea what I was getting myself into."

She stops again. "I'm going to have to think about that question," she says. "Talk to me after the show."

Because for the moment, here is the show. Panic. "Where's my script?" she calls from her chair on the set. There it is, somebody says, and just seconds to go. And now another catastrophe: Her microphone won't clip to her dress right. "This is going to have to go on a different way," says Brokaw, who tries to help. But her hands shake. There's no time," he says. Finally, the mike is clipped on, hair in place and "Good morning ," says Brokaw, "this is "Today on NBC."

A few seconds later: "And good morning, Hazard, Ky.," says Brokaw. "Town named after this program, matter of fact."

After the news, Hartley does her "Morning Line." It's wooden and she stumbles a little.

"I get so nervous for her," says her husband, a television director named Patrick Boyriven. He watches her from the set. "I have to go out and pace the corridors. I'm a backstage mother."

At 7:25 a.m., Hartley has a break. "I can't talk much today," she tells her husband. Soon she's back on the set, and Brokaw, who is set to interview a woman who's written a biograplhy of jeans designer Gloria Vanderbuilt later in the show, is introducing a woman who is the director of the Voice of America. "Here's a woman whose voice can be heard all over America," he begins.

"And so can her jeans," picks up Hartley, brightly.

Brokaw gives her a quick look.

"Oh she says on air, "that one".

Off camera, she looks out toward the studio. She grimaces toward the cameraman, draws her finger across her throat in a cutthroat maneuver, then rolls her eyes.

"I would be nowhere without my mistakes," she says later. "I rely on them.

Makes Tom look good, too."

An actress since the age of 10, Hartley has no news background. She grew up in Connecticut, did summer theater, Joseph Papp, Peyton Place on television, and "Skyjacked." But she's best known for her wisecracking role in the Polaroid commercials with James Garner. Somehow, even in a commercial, she seems pretty and nice and funny, like somebody you'd like to know.

"Jimmy and I can deal with each other in such an off-the-cuff way," she says, "people just seem to adore it."

They were attracted to it at NBC too, enough to ask an actress to take on a spot normally held by supposedly tougher women like Pauley and her predecessor, Barbra Walters. Still, they don't seem to like being reminded that she's an actress.

"I just want a bright, intelligent person," says Salant, "and she's that."

It's after the show now, and Hartley, in Pauley's office, again takes up the question of weather she wants "Today".

She doesn't answer directly, instead going through a long soliloquy about how "I know it is some women's dreams to do this kind of a show," about her children who need her, about her husband who needs her, her new production company, movies . . . "If I suddenly ended up doing this kind of a show," she says, "it would be very confusing." So is it no?

"I've never said yes," she replies.