As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
TRANSPONDER HAS CORROSION IN UNIT. PERFORMED PRELIMINARY INSPECTION AND CLEANED EXCESSIVE CORROSION ON CHASSIS. REPLACED BUSHING AND INSULATOR FOR TRANSISTOR Q104 DUE TO CORROSION. FOUND UNIT WENT OFF LINE. FOUND UNIT TO BE STAYING IN TEST MODE. REPLACED INTEGRATED CIRCUIT I402.REPAIRED PROBLEM. BENCH CHECK GOOD.