What was found
AFTER TAKEOFF, NOSE GEAR FAILED TO RETRACT. A/C RETURNED TO CVG. FOUND FLUID LEVEL OK AND LOW ON AIR. REPLACED SCHRADER VLV, RESERVICED FLUID AND AIR. A/C NOSE JACKED AND NOSE GEAR RETRACTED OK. TAXIED A/C. NOSE STRUT IS NOW HOLDING FLUID AND AIR. NO OTHER PROBLEMS NOTED.