What was found
(CAN) ON APPROACH GEAR WAS SELECTED DOWN, NOSE AND RT MAIN INDICATED DOWN AND LOCKED. GEAR WAS CYCLED 3 TIMES, ON FOURTH TRY ALL GEAR EXTENDED AND LOCKED DOWN, AIRCRAFT LANDED NO PROBLEM. AIRCRAFT FLOWN TO MAINTENANCE BASE, PLACED ON JACKS, GEAR SYSTEM TESTED SERVICEABLE. POSSIBLE CAUSE: AIRCRAFT WAS CLEANED BY FLIGHT CREW AND UPLOCK WAS NOT LUBED. ALL AIR AND GROUND CREWS HAVE BEEN ADVISED OF SITUATION. (X)