As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLIGHT 5516 - GEAR DISAGREE MESSAGE DISPLAYED UPON GEAR RETRACTION DURING TAKEOFF. NOSE GEAR REMAINED IN DOWN POSITION, MAINS SHOWED IN UP POSITION. FOLLOWED QRH, EMERGENCY DECLARED. AIRCRAFT RETURNED TO CVG AND LANDED SAFELY. ADJUSTED (S23) NLG STRUT EXTEND PROX SENSOR.