As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) TACH WIRES CHAFED THROUGH AND GROUNDING TO THE COIL PRIMARY CONNECTOR. TACH WIRES INCORRECTLY ROUTED TCM SB663A NOT COMPLIED WITH FOR WIRE ROUTING. VERY HIGH RESISTANCE FOUND BETWEEN THE TERMINALS OF THE TACH POINTS, WHEN CLOSED 1200-1500 OHMS, PROBLEM IS BLACK COATING ON TACH POINT ARM CAUSING A HIGH RESISTANCE. MAGNETO REMOVED FROM ACFT BECAUSE IT WANTED TO OVERSPEED.