What was found
GEAR WILL NOT RETRACT, HANDLE WOULD NOT MOVE. COMPLETED GEAR SWING, NO DEFECTS NOTED, CHECKED NOSE WHEEL CENTERING CHECK GOOD. COMPLETED LANDING GEAR TROUBLESHOOTING TREE FOR GEAR HANDLE FAULT, NO FAULTS FOUND IAW CE-750 M/M CHPT 32-30-00. CONNECTED DMC MONITOR BOX OPERATES GEAR SEVERAL MORE TIMES. NO DISCREPANCIES NOTED. RESTORED AIRCRAFT FOR RETURN TO SERVICE.