As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON FLIGHT 3757, CREW REPORTED LANDING GEAR WOULD NOT EXTEND. PERFORMED MANUAL/EMERGENCY EXTENSION. ENGINE HYDRAULIC PUMP PRESSURE WAS NORMAL. CREW ATTEMPTED TO EXTEND GEAR 3 TIMES BUT FAILED. DID GET A LG DISAGREE WARNING. HAD TO DO A GO AROUND TO GET GEAR DOWN. AIRCRAFT REMOVED FROM SERVICE. REMOVED AND REPLACED LANDING GEAR SELECTOR VALVE AS PER AMM 52-32-10. PERFORMED OPERATIONAL CHECK OF LANDING GEAR EXTENSION AND RETRACTION OPERATIONAL CHECK GOOD. AIRCRAFT RETURNED TO SERVICE.