As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
NR 2 ENGINE BACK FIRING, SUSPECT NR 11 CYLINDER REARS. ENGINE WAS UNABLE TO TAKE LEANING. FOUND PART OF A BROKEN BRUSH WEDGED BETWEEN INNER AND OUTER SEGMENT PLATES OF LEFT DISTRIBUTOR. REPLACED FAULTY DISTRIBUTOR WITH SERVICEABLE UNIT. REF: DAC DC-6 LMM SEC II CH 6-10-2, GROUND RUN CHECKED GOOD.