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 AND FOUND THE GEAR TEETH P/N 10-682016 BROKEN OFF OF BOTH THE LEFT AND RIGHT GEAR ASSEMBLIES. AFTER FURTHER INVESTIGATION OF THE MAGNETO, IT WAS ALSO FOUND THAT ONE OF THE RETAINER SNAP RINGS P/N 10-92815-37 TO BE DISCOLORED AND SPREAD APART.