What was found
AFTER TAKE-OFF ATTEMPTED TO RETRACT GEARS AND FOUND LANDING GEAR HANDLE WOULD NOT GO UP. ACCOMPLISHED AIR TURN BACK. FOUND NOSE STRUT NITROGEN PRESSURE LOW, NOT ALLOWING STRUT TO FULLY EXTEND TO MAKE SQUAT SWITCH. SERVICED NOSE STRUT AS REQUIRED IAW CESSNA 750 MM CHAPTER 12-10-38, OPS CHECKED GOOD WITH GEAR SWING.