As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
THE PILOT REPORTED THAT ON CHECKING THE RT MAGNETO THERE WAS AN EXCESSIVE RPM DROP BUT THAT THE ENGINE STILL OPERATED SMOOTHLY ON THAT MAGNETO. UPON DISASSEMBLY OF THE MAG IT WAS FOUND THAT ONE LEG OF THE CAM SLOT ON THE ROTOR SHAFT WAS COMPLETELY BROKEN OFF AT THE BOTTOM OF THE SLOT. (K)