As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT EXPERIENCED HARD STARTING ON RT ENGINE. LEFT MAGNETO OF RT ENGINE REMOVED AND INSPECTED. IT WAS FOUND THAT THE DISTRIBUTOR FINGER HAD BECOME LOOSE ON DISTRIBUTOR GEAR SHAFT AND WAS FREE TO ROTATE INDEPENDENTLY OF GEAR. MAGNETO REPLACED WITH SERVICEABLE UNIT.