As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING MAGNETO PERFORMANCE, CHECK PRIOR TO FLIGHT, PILOT NOTED ENGINE WANTED TO QUIT RUNNING WITH RIGHT MAGNETO SELECTED TO OFF. EXTERNAL INSPECTION OF MAGNETO LEFT CHECKED GOOD. REMOVED LEFT MAGNETO AND INSPECTED INTERNALLY. INSPECTION REVEALED .5000 INCH SECTION OF DISTRIBUTOR BLOCK BURNED AWAY. UNKNOWN CAUSE AND NO RECOMMENDATION AT THIS TIME.