As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER DEPARTURE, GEAR FAILED TO RETRACT. GEAR INDICATED 3 RED WITH GEAR HANDLE SELECTED UP. FOLLOWED QRH AND PUT GEAR HANDLE IN DOWN POSITION. INDICATED 3 GREEN AND VERIFIED GEAR WAS DOWN. AC RETURNED TO DEPARTURE AND LANDED. DID NOT DECLARE AN EMERGENCY. MX INSPECTED THE NLG AND FOUND NLG CENTERING PROX SENSOR FROZEN. LUBRICATED NLG CTR MECHANISM IAW AMM 12-20-01-640-802. PERFORMED GEAR SWINGS IAW AMM 32-31-00-710-801. NO DEFECTS NOTED.