As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING A 500 HR INSPECTION ON THE MAGNETOS, IT WAS DISCOVERED THAT IMPULSE COUPLING HAD CRACKS IN FLYWEIGHT BASE PLATE. CRACKS DETECTED USING MAGNETIC PARTICLE INSPECTION. CRACKS ORIGINATED FROM SHARP CORNERED FEATURE OF BASE PLATE THAT FORMS THE FULL ADVANCE STOP.