As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING 100-HOUR PHASE INSPECTION, MAG WAS REPLACED WITH OVERHAULED UNIT. TWO AND ONE-HALF FLIGHT HOURS LATER, MAG FAILED. FOUND CAM FOLLOWER ON BOTH BREAKER POINTS EXCESSIVELY WORN. MAG TIMING OUT OF LIMITS. SUBMITTER SUGGESTS MFG CHANGE FROM PHENOLIC TO PLASTIC CAM FOLLOWER MATERIAL TO BE THE CONTRIBUTING FACTOR.