IT'S LATE in the afternoon on a mid-January day a few hours before the filming of the episode of "Cheers" that will run tomorrow night. A member of its cast is being shadowed by a man in a sport coat and tie with the serious but distracted look on his face that comes when you're listening to earphones HTC connected to a walkie-talkie.
He's an assistant director -- an A.D. in sitcom slang -- whose priority right now is to keep track of this actor so he can be summoned to the set when needed.
"A.D.'s, the actor's natural predator," the cast member mutters as he relaxes in a lounge near his dressing room. "Actually, they almost have to assign one to each of us, we're so bad."
Indeed, the cast of "Cheers" seems something like a class of exceptionally gifted high school students. Sure they're a little unruly, but they know they're smart, they know they're going to ace the test, so why do they have to stay in their seats and face the teacher all day?
You'd probably be a little frisky, too, if you were an actor in "Cheers." The show is on a virtually unprecedented roll. In its ninth year, when most comedies are held together by Scotch tape and casting gimmicks, "Cheers" is soaring.
It was the No. 1 show for the year that ended last September and will certainly be the top-rated series for this season. This from a show that could hardly get friends and family to watch when it went on the then-struggling NBC in 1982.
The mischief on this Wednesday afternoon was heightened by the absence of Jim Burrows, one of the show's creators who has directed almost every episode of the more than 200 that have been made. Andy Ackerman, a "Cheers" Emmy-winning editor, who is directing about a half dozen episodes this season, was in charge.
"Jim is like the leader of the Boy Scout troop," one of the show's staff members said. "They all know when they can mess around and when he's serious."
With Ackerman, it was like having a substitute teacher. Everyone seemed to push the limits a bit, just to find out what you could get away with. But what passes for testiness on the "Cheers" set would be a love-in on many series. All of them, Ackerman included, are skilled artisans who respect one another's ability, and they also happen to be friends.
"Everyone pretty much gets along," co-executive producer Phoef Sutton said. "Sure there are some disagreements, but it's not like some shows I've written scripts for where you just want to get out of there as soon as possible."
That friendly atmosphere not only helps the "Cheers'" crew put its energy into the show, but it is also perhaps the most important reason that there has been only one defection from the cast in its nine years.
Money, in part because of a syndication deal that allows for large salaries, certainly has something to do with that, but usually after five years or so, some members of a cast are lured away by the movies or promises of a starring role in a new show.
Not with "Cheers." The core of Ted Danson as Sam Malone, Rhea Perlman as Carla Tortelli, George Wendt as Norm Peterson and John Ratzenberger as Cliff Clavin has been together since the beginning. The brilliant character of Coach died with Nicholas Colasanto in 1985, but he was replaced by Woody Harrelson's hilarious rendition of Woody Boyd.
What could have been the most telling blow came when Shelley Long became the only defection, taking Diane Chambers with her in 1987. Burrows said that the staff took this as something of a challenge.
"We wanted to prove that the show was not just built on one person or one relationship," he said. "Shelley was not the central character.
"Look, we've had the misfortune and good fortune to lose a couple of key people. It was our misfortune to lose them, but our good fortune to be able to replace them with different types of characters."
Indeed, unlike some older sitcoms that have all sorts of extra characters hanging around just to tell jokes, "Cheers" has evolved rather naturally.
Also unlike many aging comedies, "Cheers" has stayed right on its original premise, remaining a show about the people who work and drink at this bar.
"It's a simple premise and that helped," Sutton said. But Sutton also has a more basic theory for the continued success of "Cheers."
"It's something that tends to get overlooked, but I think it's just because the show is funny," he said. "That's the whole point of the show. It's character-oriented and reality-based, but what we try to do every week is be funny, nothing else.
"I think it's like an old shoe," Burrows said of this popularity in relative old age. "It's been re-soled and gotten a few new heels over the years, but it's very comfortable."
On the day of the filming, the cast and crew run through the episode scene by scene, as the scores of extras get their complicated choreography down so that they are always in the right place with the right drink in the right hand no matter how many times a scene is filmed.