Eric B. & Rakim have gone back to the well too many times, retaining the technique without maintaining the energy. After their groundbreaking 1987 debut, they've stayed put with Rakim's laid-back chilly delivery and Eric B.'s James Brown collection. On their fourth album, Don't Sweat the Tecnique, they've added explicit appeals and a touch of jazz to ''Teach the Children.'' If the entire collection maintained the roller coaster rush of ''Teach'' or ''Casualties of War,'' no one would mind but it doesn't.