What was found
RAISED THE GEAR HANDLE AFTER DEPARTURE, GEAR DID NOT RETRACT. WE HEARD A LOUD GRINDING NOISE FROM THE NOSE WELL. JACKED ACFT. HOOKED UP MULE, WITH 1500 PSI, GEAR CAME UP. ALL 3 IN-TRANSIT LIGHTS REMAINED ON AND GEAR HANDLE FLASHED. CYCLED GEAR DOWN, ALL 3 GREEN LIGHTS ILLUMINATED. (EL)(DS) REMOVED PRESSURE AND NOSE GEAR STARTED TO DROP. NLG UPLOCK ASSY NOT HOLDING NLG. FOUND AMM FOR MANUAL RELEASE JAMMED AND WILL NOT MOVE. R & R NOSE GEAR UPLOCK BOX AND OPS CHECKED GOOD IAW MM 32-22-17-900-801.