As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PILOT FOUND 250 RPM MAG DROP, LT MAG. TROUBLESHOT IGNITION SYSTEM. REMOVED MAG AND FOUND EXCESS PLAY IN IMPULSE COUPLING AND MAG DRIVE. SENT OUT FOR REPAIR, SPRING WAS BROKEN. SUSPECT IMPROPER INSTALLATION OR DEFECTIVE METALLURGY PRIOR TO INSTALLATION.