As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON A GROUND RUN UP, PILOT REPORTED A BAD MAG DROP. AFTER PULLING MAGNETO OFF OF THE ENGINE, IT APPEARS THE MAGNETO FAILED. THE PLASTIC DRIVE GEARS WERE STRIPPED AS WELL AS THE MAGNETO RETAINER DRIVE COUPLING AND DRIVE COUPLING RUBBER BUSHING WERE DAMAGED. NO OTHER DAMAGE WAS FOUND ON THE ENGINE.