What was found
BIL - AFTER TAKEOFF, GEAR WOULD NOT FULLY RETRACT WHEN SELECTED UP. GEAR WAS SELECTED DOWN, AND DOWN AND LOCKED WAS INDICATED. GEAR WAS CYCLED 4 TIMES TO THE DOWN POSITION WITH NO POSITIVE INDICATION. GEAR WAS HAND-PUMPED DOWN, AND AIRCRAFT LANDED WITHOUT INCIDENT. LEFT REAR MLG DOOR ACTUATOR SHAFT O-RING LEAKED. REPLACED O-RINGS ON THE ACTUATOR. LEAK CHECK AND OPS CHECK OKAY.