What was found
NLG FAILED TO RETRACT AFTER TAKE OFF. RED UNLOCK LIGHT ILLUMINATED. HEARD FOUR BUMPS AND FELT THROUGH AIRFRAME. RED ITEMS CHECKLIST COMPLETED WITH A NORMAL UNDERWEIGHT LANDING. JACKED ACFT. CHECKED OPERATION OF LANDING GEAR. NOSE GEAR RETRACTED NORMAL. NOSE GEAR UNSAFE LIGHT STAYED ON ALONG WITH A BUMPING NOISE FROM THE NLG AREA. CHECKED NOSE GEAR UP SWITCH FOUND SWITCH PLUNGER STICKING. LUBED SWITCH, OPERATES SATISFACTORILY. REMOVED NLG UPLOCK SWITCH, AND REPLACED WITH NEW SWITCH IAW MM 32-60-00. OPS CHECKED GOOD.