April 10, 1987

LEAD: In past years, Lynbrook High School had always been knocked out in preliminary rounds of WLIW Channel 21's quiz show, ''Brainstormers.'' ''We never even made it to the televised rounds,'' said the coach, Mimi Butler, a guidance counselor.

LEAD: Three bullet holes and the aluminum jacket of a pistol bullet were found yesterday in the gas meter of a South Bronx grocery store where six people died in an explosion Wednesday, the police said.

LEAD: Camp Smith, a key training site for ground combat units of the state's Army National Guard, assumed a new support role this week: housing General Motors Corporation workers transferring to this region.

LEAD: EASTER is music's time for storytelling. Thus Holy Week - the unfolding narrative of Jesus' passage to the cross - evokes powerful musical drama that, in turn, enriches the power of the event itself.

LEAD: Friday HUNGARIAN FILM VIEW Over the past two decades, Gyula Gazdag, a Hungarian film maker, has produced a wry and iconoclastic body of work unusual in the carefully controlled artistic milieu of Eastern Europe. This evening at 6:30, Mr. Gazdag will appear at the Museum of Modern Art, 11 West 53d Street, to introduce his 1974 operatic parody ''Singing on the Treadmill,'' a satire of the Socialist Realist works of the 1950's.