What was found
UPON GEAR RETRACTION, GEAR DOORS LIGHT & RIGHT MAIN GEAR UNSAFE LIGHTS REMAINED ILLUMINATED. RED TAB PROCEDURES ACCOMPLISHED. WHEN INITIALLY MOVING, AND BEFORE REACHING THE "OFF" POSITION, IT APPEARED A HYDRAULIC SURGE OCCURRED , WITH A CORRESPONDING "BUMP" AND BOTH LIGHTS EXTINGUISHED. REMOVED AND REPLACED MAIN LANDING GEAR LOCK OPERATED SEQUENCE VALVE PER 727-100 MAINTENANCE MANUAL 32-32-031-4, OPERATIONAL CHECK GOOD PER 727-100 MAINTENANCE MANUAL 32-32-00-5. OK FOR SERVICE.