THERE'S SOMETHING MYTHICAL about the daring crook who manages to pull off the perfect heist. From England's great train robbers to the parachuting D.B. Cooper, these characters usually grab public attention for a few weeks on the front pages, and then pass quietly into the annals of folk-mythology.

This is certainly true of Boston's Brink's robbers. Far from being a gang of master criminals--as was first supposed--the thieves turned out to be nothing more than a bunch of petty, two-bit bumblers who hung out in Scolley Square, pulling off little jobs and dreaming of the big heist. It seemed poetic justice that these ordinary crooks were the ones to hit the prestigious armored-car company for a million and a half dollars. It was a daring robbery, no one got hurt, and the crooks very nearly got away with it. It's the stuff of legends.

In The Brink's Job this legend is played for all it's worth--even more than it's worth. Director William Friedkin is so intent on showing the lovable underdogs who made it big that he bogs the tale down.

The film loosely follows the actual robbery which took place in Boston's North End back in 1950. That one was concocted by 11 men, seven of whom slipped into the Brink's warehouse one evening wearing pea-coats and Halloween masks and made off with the loot. At the time, the Brink's gang wasn't looked on as a bunch of affable fellows who just happened to stumble onto the crime of the century. In fact, a lot of people were convinced that the gang had wide underworld connections. Even six years after the robbery, when the case finally came to trial, the judge had difficulty empanelling jurors, most of whom were convinced they would be marked for life if they handed down a guilty verdict.

Of course, such details are not the things that pass into legends--or even movies. Predictably enough, The Brink's Job is nothing but distilled cuteness. It ignores all of the unphotogenic aspects of the gang, and focuses on its incompetence, its sleazy-but-sweet background, and its delight in hoodwinking the country.

This glossing over isn't really a bad thing. The Brink's legend has entertained people for more than 20 years now, and there's no reason to try to do anything more than that with the movie. Friedkin was not even a bad choice for the man to do it. Although he has a reputation from The Exorcist and The French Connection as a calculating director who stops at nothing to wrench an audience's guts, he also has done this sort of nostalgic tribute before. The Night They Raided Minsky's was a rollicking adventure about vaudeville in America. But since then Friedkin seems to have decided that he would also stop at nothing to put an audience into hysterics, and his dogged attitude ends up killing all of the fun of the Brink's legend.

The blame must be with Friedkin, since the cast couldn't be better. The Brink's gang is played by a bunch of lovable actors who delight in the roles of these bumbling underdogs. Heading the group is Peter Falk as the mastermind--if you can call him that--of this near-perfect heist. His criminal genius is somewhat in doubt, since the movie opens with one of his novice efforts, the burglary of a sausage factory. After much tool-dropping and other displays of incompetence, the job ends with Falk hiding in a room full of chickens, only to be hauled off to jail by a feather-covered cop. Undaunted, the hero emerges six years later, worried only about catching up on his back comic-book reading and planning more jobs.

NOT A BAD start. With the happy jazz of the '40s playing in the background, Friedkin sets out on a non-stop, all-out, giggly trip down bum's row. Unfortunately, the movie seems to have borrowed its sense of humor from the '40s as well, with no attempt to update it. Every old gag in the book makes its way into the film. Safes fall out of windows and just miss unsuspecting pedestrians, people keep bumping into each other, the odd-tasting pot of beef stew turns out to have a shoe in it. These tired routines would be forgivable if Friedkin didn't seem so convinced that they were original, and worthy of painstaking treatment.

None of this helps the film much. The slow pace leaves the Brink's gang looking like the Three Stooges on quaaludes. Falk and his cohorts Paul Sorvino, Allen Goorwitz and Peter Boyle (whose intermittent Irish accent has to be heard to be believed), all ham up their little peculiarities, but things never quite start rolling. The pace starts to pick up midway through the film, when Warren Oates appears as a half-crazed demolition expert whose plans to blow up the Brink's safe with a bazooka stun the rest of the gang into disbelief. But he's not on for long, and things quickly return to their former speed. The cast tries hard, but Friedkin's stodginess dooms them.

Falk sometimes manages to escape the director's slow pace. His portrayal of the thief with the heart of gold never falters. When he accidentally discovers that the Brink's fortress is no more than a poorly protected warehouse of money waiting to be hit, he rushes out and buys his wife a 100 per cent muskrat coat to celebrate his upcoming job.

The robbery itself does not come off so well. The repetive humor kills any suspense, and even Falk can't save it--his antics are inspired but predictable. Friedkin tries to enliven the end of the film by dragging in J. Edgar Hoover for a little fun. But Hoover comes off as the same old commie-hating tyrant everyone has seen before. Friedkin fails to embellish this stock figure in any way. It isn't terribly original and it's not funny to boot.

If it weren't for the director's dead-weight, this movie could probably rollick to success. All the elements are there--from Falk's bumbling to Warren Oates's sensitive performance of the gang member who cracks and blows the whistle on the thieves just two weeks before the statute of limitations runs out. Even the post-war Boston setting is faithfully captured, right down to the graffiti on the subways. But the film never takes off. At the end the robbers are led, one by one, past cheering crowds outside the courtroom. It's staged curtain call for the men who gave us the Brink's legend, but the movie doesn't do that legend justice. Like the thieves, Friedkin comes very close to pulling The Brink's Job off, but he bungles the timing.