As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING ROUTINE FLIGHT ENGINE BECAME ROUGH. PILOT CONTINUED TOWARDS AIRPORT, WITH NO OTHER OPTIONS, AND LANDED SAFELY. ONCE ON THE GROUND, THE PILOT/ MECHANIC DID AN ENGINE RUN-UP AND FOUND LEFT MAGNETO DEAD. FURTHER INSPECTION REVEALED A HOLE BURNED THROUGH THE COIL CASE INSIDE THE MAGNETO. NEW COIL AND INSPECTION PUT AIRCRAFT BACK IN SERVICE.