As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLIGHT 5535 - LEFT MAIN GEAR DISAGREE AFTER GEAR SELECTED UP. FOLLOWED QRH, THREE GREEN AFTER MANUAL GEAR EXTENSION. EMERGENCY DECLARED AND AIRCRAFT RETURNED BACK TO CVG AND LANDED SAFELY. REMOVED AND REPLACED LEFT MLG DOOR BELL CRANK.