As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
MAGNETO FAILED. DRIVE GEAR SEIZED DUE TO IMPULSE COUPLING GETTING JAMMED ON HOUSING. CAUSED MAGNETO DRIVE GEAR TEETH TO BE STRIPPED OFF BY ACCESSORY DRIVE GEAR IN ENGINE. SEVERE ENGINE ROUGHNESS DURING TAKE OFF ROLL RESULTED IN ABORTED TAKE OFF.