As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PILOT REPORTED PARTIAL POWER/ROUGH-RUNNING ENGINE PRIOR TO TAKEOFF, RETURNED TO MAINTENANCE HANGAR. MAINTENANCE PERSONNEL REMOVED D6LN-3000 DUAL MAGNETO AND DISCOVERED SEVERAL DOZEN TEETH MISSING BOTH DISTRIBUTOR GEARS. MAGNETO INSTALLED NEW ON 28 MAY, 2007.