As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CLE FLIGHT NR 3899 CREW REPORTED THAT THE NUMBER 1 TRANSPONDER NO MODE "C". NUMBER 2 TRANSPONDER ALREADY ON MEL. RETURNED TO CLE AND LANDED WITHOUT INCIDENT. MAINTENANCE INSPECTED, AND REMOVED AND REPLACED THE NUMBER 1 TRANSPONDER. SYSTEM OPERATIONAL CHECKS GOOD. AIRCRAFT WAS RELEASED TO SERVICE.