As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DEN - FLIGHT 4339 - ON APPROACH, WITH THE GEAR SELECTED DOWN, THE GEAR DID NOT EXTEND. THE CREW ALSO NOTED GEAR DISAGREE WARNINGS WITH AN ASSOCIATED PROXY SYSTEM STATUS MESSAGE. THE CREW EXTENDED THE GEAR USING THE ALTERNATE RELEASE METHOD AND RECEIVED GOOD GEAR DOWN INDICATIONS. THE LANDING WAS UNEVENTFUL. MAINTENANCE INSPECTED THE SYSTEM AND REPLACED THE LANDING GEAR SELECTOR VALVE. OPERATIONAL CHECKS WERE GOOD AND THE AIRCRAFT WAS RETURNED TO SERVICE.