As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
'ENGINE WON'T START' - 766.8 HRS HOBBS. FOUND DISTRIBUTOR GEAR M3056 BURNED. FOUND THE MS20822 FITTING TO PRESSURIZE THE MAGNETO HAD BEEN SCREWED INTO THE OUTER CASE AND BOTTOMED OUT AGAINST THE DISTRIBUTOR HEAD M3820. SUBMITTER SURMISES THE LACK OF PRESSURIZING AIR CAUSED ARCING THAT, IN TURN, BURNED THE NYLON DISTRIBUTOR GEAR M3056. REPLACED MAGNETO, TRIMMED FITTING MS20822 SO IT WOULD NOT COME IN CONTACT WITH DISTRIBUTOR HEAD. REF: 40-2350.