"Chu Chu and the Philly Flash" must have sounded like a swell idea for a zany-poignant crowd-pleaser of a movie. A likable hobo quits the booze and determines to earn the bus fare toward his first job opportunity in 20 years. An eccentric dance instructor, down on her luck and short on her rent, is reduced to performing a novelty routine on street corners. While looking for their break, they find each other.

The execution of this swell idea, alas, was its execution.

Alan Arkin, as the Flash, a former relief pitcher for the Philadelphia Phillies, is introduced awaking on a bench in a public terminal in San Francisco. Arkin, whose specialty is a look of dazed unpredictability, is rather too convincing a bum for comfort. When he stops passing motorists to wash their windshields, you can't blame them for feeling threatened.

Carol Burnett, as the embattled dance instructor Emily Laedecker, meanwhile is having her own problems. She has but one student, a hopeless one at that, and a landlord who pins eviction notices on her door. To make ends meet she dons a costume of tropical fruit and performs on street corners as "Chu Chu the One-Person Latin Band," clapping cymbals with her knees.

The paths of these two zanies cross when a briefcase literally falls on them from above -- dropped by a trio of squabbling bad guys. Philly and Chu Chu make off with the briefcase, intending to ransom it and perhaps divide the windfall. But the briefcase -- which contains documents of a value never made clear -- is of course more trouble than they expect.

Lest fascination with the main characters flag, and it does straight away, the film provides a set of backround zanies -- the half-dozen hobos led by Jack Warden, who exercises economic control over them from his home on a barge moored in the China Basin. Warden, unfortunately, is unpleasantly loud throughout and his lines are peppered with the needless vulgarities that have become the stock in trade of PG-rated movies. Among the hobos are Ruth Buzzi, who gets little to do, and Adam Arkin, a large youth with a perplexed look and a nice way with a deadpan line.

"Chu Chu and the Philly Flash" is a movie with the charm of a rehearsed ad lib. It is tiresomely zany and then, precisely on schedule, tiresomely poignant. Arkin and Burnett seem vaguely aware of what is happening as the film progresses, but they are unable to do much about it because they are stuck in a love story without a kiss or a nuzzle, and a comedy without a single memorable line.

Too bad. It must've sounded swell on paper.