As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
TRANSPONDER REPLIED ERRATICALLY. REPLIES WERE NOT SYNCHRONIZED WITH INTERROGATIONS. REPLACED LEAKY CAPACITOR C441. DEFECTIVE PART HAD BLACK EPOXY COATING. REPLACEMENT PART HAD TAN COATING. PROBLEM DISAPPEARED. IN ADDITION, TRANSPONDER AUTOMATIC OVERLOAD CONTROL WAS INEFFECTIVE. REPLACED LEAKY CAPACITOR C437. SAME COLORS AS ABOVE. PROBLEM DISAPPEARED. VERY COMMON PROBLEM.