What was found
(CAN) DURING A ROUTINE MAINTENANCE CHECK THE LEAKING LEFT UPLOCK ACTUATOR WAS REPLACED WITH AN OVERHAULED UNIT. ON GEAR RETRACTION TEST, THE LEFT GEAR WOULD NOT EXTEND FULLY. THE GEAR WOULD UNLOCK AND FALL, BUT NOT EXTEND TO THE LOCKED POSITION. DUE TO THE NATURE OF OPERATION, THE BALL P/N 5272-5 WAS SUSPECTED TO BE MISSING. THIS WAS CONFIRMED AFTER A PARTIAL DISASSEMBLY OF THE ACTUATOR. (X)