As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DISTRIBUTOR GEAR ROTOR CAME LOOSE FROM GEAR AND INTERFERED WITH ALL SIX BLOCK TERMINALS CAUSING BRASS DUST TO BE GROUND FROM TOWERS AND CONTAMINATED MAGNETO INTERNALLY. BRASS DUST WAS VISIBLE THROUGH TIMING PLUG ACCESS HOLE DURING ROUTINE MAGNETO TO ENGINE TIME CHECK. MAGNETO REMOVED FROM SERVICE AND REPLACED WITH AN O/H UNIT.