As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
EWR---CO3540, CREW REPORTED "LANDING GEAR DISAGREEMENT ON MAIN GEAR. AIRCRAFT AIR RETURNED" (TO NEWARK WITHOUT INCIDENT).....MAINTENANCE TROUBLESHOT AND REMOVED AND REPLACED RIGHTHAND MAIN LANDING GEAR UPLOCK IAW EMB145 AMM #32-33-10. OPS. CHECKED GOOD. AIRCRAFT RETURNED TO SERVICE.