As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PILOT REPORTED THAT THE MAGNETO WOULD FAIL ON RUN UP. TROUBLESHOT THE SYSTEM AND FOUND THE MAGNETO INTERIOR COATED IN BRONZE LIKE METAL FLAKES. DETERMINED THAT THE BLOCK BEARING HAD FAILED AND THE ROTOR HAD CHAFED THE POINTS DOWN. THE MAGNETOS HAD BEEN OVERHAULED BY TCM UNDER THEIR WO NO P53955. DISTRIBUTOR BLOCK PN 10-391586