What was found
CREW REPORTED ON APPROACH GEAR EXTENDED THREE GREEN LIGHTS AND THREE RED BACK UP GREEN GEAR LIGHT ON. ON APPROACH GROUND PROXIMITY WARNING SYSTEM AUDIO TOO LOW GEAR. RECYCLED GEAR WITH SAME INDICATIONS. EMERGENCY DECLARED FLIGHT LANDED SFO WITHOUT INCIDENT. AIRCRAFT REMOVED FROM SERVICE. FOUND GEAR CONTROL LEVER SHAFT NOT FREELY MOVING INTO/OUT OF DETENT. CLEANED LANDING GEAR LEVER SHAFT. SYSTEM GROUND CHECK NORMAL OPERATION.