As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PILOT REPORTED THAT THE ENGINE IS RUNNING ROUGH DURING TAXI AND HAD A BAD MAGNETO DROP. MAINTENANCE INVESTIGATED THE PROBLEM AND DETERMINED THAT THE MAGNETO P/N 10-682560-13 NEEDED TO BE REPLACED. UPON FURTHER INVESTIGATION OF THE MAGNETO, FOUND THAT 2 EACH OF P/N 10-682016 HAD BROKEN TEETH ON THE GEAR ASSEMBLIES.