As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
C/W INSPECTION ITEM NR 9. REMOVAL OF ROCKER BOX COVERS EA400 HOURS AND FOUND EXCESSIVE EXHAUST DEPOSITS ON AND AROUND VALVE SPRINGS. C/W LYC SB 388B. EXHAUST VALVE GUIDE WEAR TO BE VERY EXCESSIVE .050 INCH PLUS ON FIVE OF THE SIX CYLINDERS, 837.00 HOURS SINCE NEW. SUBMITTER SUGGESTS VALVE FAILURE WAS IMMINENT WHICH COULD CAUSE TOTAL LOSS OF POWER.