What was found
(CAN) DURING CIRCUIT FLYING, TOWER REPORTED TO PILOT THAT HIS TRANSPONDER WAS INTERMITTENT. PILOT CANCELLED REMAINDER OF FLIGHT AND RETURNED TO AIRPORT. DEFECT WAS NOT DUPLICATED ON THE GROUND. DEFECT OCCURED THE NEXT DAY WHILE AIRCRAFT WAS AGAIN IN THE CIRCUIT, PILOT CANCELLED AND RETURNED TO AIRPORT. MAINTENANCE REMOVED TRANSPONDER, CLEANED CONTACTS AND RE-RACKED TRANSPONDER. AIRCRAFT RETURNED TO SERVICE AND HAS NOT HAD ANOTHER OCCURANCE IN OVER 50 HOURS. (TC NR 20070228007)