As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
MAGNETO WAS DISASSEMBLED FOR 500-HOUR INSPECTION. WEAR ON FLYWEIGHT AXLES WAS APPROXIMATELY .020 INCH AND STOP PINS HAD GROOVES ABOUT .020 INCH DEEP. IMPULSE COUPLING SPRING WAS BROKEN. AIRCRAFT WAS OPERATED 80 HOURS IN PAST 5 YEARS. NOT FLOWN AT ALL FOR PAST 4-1/2 YEARS. INFREQUENT OPERATION AND LACK OF MAGNETO MAINTENANCE LEAD TO A SITUATION THAT COULD HAVE CAUSED ENGINE FAILURE.