What was found
(CAN) FLIGHT CREW WAS UNABLE TO SECURE LANDING GEAR IN UP POSITION. THE FLIGHT RETURNED FOR SAFE LANDING. MAINTENANCE WAS DISPATCHED AND FOUND THE LT GEAR UP LOCK HOOK STUCK AND FROZEN IN THE UP POSITION. ASSY WAS DISASSEMBLED, MOISTURE REMOVED, CLEANED AND LUBED AND REASSEMBLED. NUMEROUS GEAR SWINGS PERFORMED, ALL CHECK SVC.