As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DEN - ON FLIGHT 4310, RETURNED TO FIELD. GEAR DIAGREE WARNING MESSAGE ON TAKEOFF WHEN GEAR SELECTED UP FOLLOWED BY PROX SYSTEM FAULT STATUS MESSAGE. AIRCRAFT LANDED WITHOUT INCIDENT. MAINTENANCE REALIGNED CENTERING CAM RETAINER AND REPACKED NOSE LANDING STRUT. OPERATIONAL CHECK OF EXTENSION AND RETRACTION GOOD. NO FAULTS NOTED. AIRCRAFT RETURNED TO SERVICE. NO PARTS REPLACED.