A few Top 40 hits and a fatal plane crash. How many films can be squeezed out of this formula? O.K., The Buddy Holly Story and Patsy Cline's Sweet Dreams were good movies. But . . . La Bamba? Ritchie Valens was only 17 when he, Holly and J.P. ("Big Bopper") Richardson died in 1959. His music is surely worth remembering; his life is hardly worth dramatizing. So Writer-Director Luis Valdez shapes facts into fable. Valens' family is a chicano caricature; death forever stalks our shooting star; chunky Ritchie is made over into winsome Lou Diamond Phillips. Even the music (by Los Lobos) sounds thin next to the originals, with their booming bass lines. Only at a concert with Jackie Wilson and Eddie Cochran does La Bamba come alive as a sharp tribute to '50s rock from some sons of the pioneers. The rest of the movie plays like a 106- minute version of a teen ballad: Donna in the easy-listening remix.