As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
SHORTLY AFTER TAKEOFF, THE CREW SELECTED GEAR UP BUT THE GEAR DID NOT RETRACT. THE CREW DID AN AIR-TURN-BACK AND HAD AN UNEVENTFUL LANDING. MECHANIC INSPECTED THE SYSTEM AND REPLACED THE HYDRAULIC SERVICE VALVE. MECHANIC OPS CHECKED THE SYSTEM WITH NO FURTHER DEFECTS AND RELEASED THE AIRCRAFT BACK TO SERVICE.