As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PILOT MADE PRECAUTIONARY LANDING WHEN LEFT ENGINE GOT ROUGH IN-FLIGHT. ENGINE WOULD NOT RE-START ON GROUND. FOUND LEFT MAGNETO SEVERELY CORRODED INTERNALLY. INVESTIGATION REVEALED RIGHT MAGNETO ON LEFT ENGINE AND BOTH MAGS ON RIGHT ENGINE IN SAME CONDITION, BUT HAD NOT FAILED YET. FOUR NEW MAGS INSTALLED IN AIRCRAFT.