As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING A 500 HOUR INSPECTION OF MAGNETO, A CRACK WAS DISCOVERED IN THE IMPULSE COUPLING BASE PLATE. CRACK ORIGINATES AT THE ADVANCE STOP NOTCH OF THE FLYWEIGHT BASE PLATE. CRACK DISCOVERED USING MAGNETIC PARTICLE INSPECTION NDT. IMPULSE REPLACED WITH NEW. HAVE SEEN THIS SAME DEFECT ON A LARGE PERCENTAGE OF MAGS USED ON THESE SERIES ENGINES.