What was found
AFTER TAKEOFF, THE LANDING GEAR LEVER REMAINED LOCKED IN THE DOWN POSITION. GEAR WOULD NOT RETRACT. TROUBLESHOT ISSUE TO NGL SQUAT SWITCH NOT BEING CLOSED DUE TO PARTIAL SHOCK STRUT EXTENSION. REMOVED LH AND RH NLG WHEELS, CLEANED AND SERVICED STRUT, RE-INSTALLED LH AND RH NLG WHEELS, PERFORMED GEAR SWING, OPS CHECK GOOD, AND SERVICED HYDRAULIC RESERVOIR. ALL WORK PERFORMED IAW CESSNA 750 AMM: 32-30-00, 32-41-01, 32-00-01, 12-10-15, & 12-10-38.