As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
MAGNETO LT/ MAG, P/N 4371 S/N 96110203 INSTALLED ON AN ENGINE, EXPERIMENTAL ACFT. MAGNETO HAD A ROUGH RUNNING ENGINE, UPON INVESTIGATION FOUND THIS CONDITION, ALTHOUGH THIS WAS NOT THE CAUSE OF THE ENGINE RUNNING ROUGH, IT APPEARS THAT THE CAM AND DRIVE GEAR WAS NOT FULLY SEATED ON THE SHAFT DURING MFG. THE WEAR IN THE BLOCK ASSY. WAS ABOUT .01 DEEP AND WITH NO VISIBLE WEAR ON THE DRIVE GEAR.