As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(AUS) DURING PERIODIC INSPECTION, NR 4 CYLINDER COMPRESSION WAS 20/80. THE EXHAUST VALVE P/N 646286 WAS REMOVED AND FOUND TO BE WORN 0.203 MM (0.008 INCH) JUST ABOVE STEM NECK. THE VALVE GUIDE P/N 643767 WAS WORN 0.457 MM (0.018 INCH) AT THE LOWER HALF AREA.