As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) DURING PRE-TAKEOFF GROUND RUN MAGNETO FUNCTION CHECK, PILOT NOTICED LT MAGNETO NOT WORKING. MX REPLACED MAGNETO AND RETURNED ACFT TO SERVICE. MAGNETO OPENED UP AND PLASTIC DUST PARTICLES WERE FOUND THROUGHOUT AND ON POINTS. DRIVE GEAR HAD MIGRATED UP AND WORN THROUGH MAIN DISTRIBUTOR GEAR CAUSING THE DUST PARTICLES. MAGNETO WAS INSPECTED APPROX 300 HOURS EARLIER IAW MANDATORY 500-HR INTERNAL INSP AND WAS FOUND SATISFACTORY.