Off the cuff, Mel Brooks is one of the world's funniest talkers -- a spritz artist par excellence. In interviews, the words tumble out in a mad, inspired rush, one character, one voice, taking the stage almost before the previous one has left it. Alone or paired with his favorite partner, Carl Reiner, he's a legendary improviser, dinner-party entertainer, talk-show guest. I'm guessing his lunches are masterpieces.

His movies, unfortunately, are not -- even his best -- and his latest, "Spaceballs," a parody of the space adventure genre, is one of the worst of the bunch.

A pre'cis of the film's plot is not necessary: Suffice it to say that there are a passel of jokes -- one coming roughly every 20 seconds -- made at the expense of "Alien," the "Star Trek" movies and the "Star Wars" films, with the latter taking the brunt of the attack. Thrown in for seasoning, as well, are jokes about sequels and movie merchandising -- "Spaceballs" dolls, "Spaceballs" breakfast cereal, and, of course, the "Spaceballs" flame thrower -- which Brooks sees as having been a side effect of Hollywood's space program.

The jokes in the films are all pretty much in the same vein -- you might call it borsch-belt postmodern -- and they're all on about the same level, too. The only truly successful gag comes early on, when, after the opening scrawl (which tells us, "If you can read this, you don't need glasses"), a spaceship rumbles into the frame, as largish spaceships often do in space films, and keeps rumbling on -- for a good minute and a half.

The movie isn't aggressively, raucously unfunny, like, say, "Outrageous Fortune" or "Blind Date." It seems, in fact, like a much less fussed-over, lower-priority affair, like a production in some backwater dinner theater. (But then isn't that what anything with Dick Van Patten in it would look like.) The production design is strictly from hunger, and the costumes don't seem to have been thought out in terms of getting laughs; they're missing that next level of conceptualization that might have made them funny. As it is they're just clothes.

We wouldn't be quibbling over such things if the whole film weren't missing that extra, essential layer. What you're conscious of throughout this movie is that you're sitting in your seat, not laughing at performers who desperately want you to laugh. Rick Moranis has a few good moments mugging to the camera as the Darth Vader character, Dark Helmut. The director himself plays two characters, the shorter of which is a greenish, gnomish, yiddish-ish little sage called Yogurt. Yogurt's catch phrase, and the movie's, is "May the Schwartz be with you." And for this you hire writers?

In his other role, of President Skroob, leader of Spaceballs, the planet -- to whom he gives a pert little "Monsieur Verdoux" moustache -- Brooks has a couple of almost-passable scenes, like the one in which he tries, with disastrous results, to have himself beamed up -- "Star Trek"-style -- into the next room.

What you're laughing at (or nearly laughing at) in these sequences is the idea, the hint, of Mel Brooks being funny. He's built up tremendous good will over the course of his career. And we give him the benefit of the doubt, we're more patient, in a way we might not be with other comedians.

Two other comics in the film, Moranis and John Candy (who plays Barf, the half-man, half-dog, Chewbacca character), are somewhat spared by some of the same audience largess. (The great John Candy performance, we keep hoping, is still out there somewhere, waiting for takeoff.) But the talents of both performers are squandered.

The other principles, Bill Pullman and Daphne Zuniga (in the Luke Skywalker and Princess Leia roles) aren't so lucky. Pullman is like a parody of what he's parodying. And Zuniga, whose character is a "Druish" princess -- as in "funny, she doesn't look Druish" -- with a robot maid named Dot Matrix (with a voice provided by Joan Rivers, who, by the way, has never looked better), is stuck with a one-joke part and little in the way of natural resources to help her through.

Brooks seems to have run out of gas in his movie takeoffs. Watching this new one, you get the feeling that he's just going through the motions with his genre series -- that as long as there are genres there will be Mel Brooks genre-parodies. And for no other reason than that they are there to do. (Anyway, isn't it a little past the moment to be doing a "Star Wars" spoof -- like maybe by about 10 years?)

There's no inspiration left -- no drive. After that first joke, which at least gets you tittering, I don't think there's another first-rate comic idea in the whole film. And most of what he comes up with is achingly unfunny. Brooks' directorial style, which, summed up briefly, is, line 'em up in front of the camera and shoot 'em, flattens everything out. To say that it's sub-"Mad" material isn't really fair: "Mad" can be pretty dead-on in its movie parodies.

"Spaceballs" is actually a kind of comic black hole. All in all, the movie is about as funny as having coffee spilled in your lap. Except that there's no burn -- just that slightly embarrassing, uncomfortable, all-wet feeling. Brooks is a man of some taste: His production company, Brooksfilms, participated in the making of "Frances," "The Elephant Man" and "The Fly." But maybe it's time for him turn over the directing chores to somebody else. He can spot talent, so why can't he place himself and his real, natural gifts in the hands of someone who might put them to better use -- to let Mel Brooks, the genius talker, onto the screen. Spaceballs, at area theaters, is rated PG, and contains no objectionable material.