As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WHILE PERFORMING SB388B THE NR 4 EXHAUST VALVE PUSHROD WAS FOUND BENT. THE NR 4 CYLINDER EXHAUST VALVE MUST HAVE STUCK AT SOME POINT CAUSING THE PUSHROD TO BEND. THIS MAY HAVE OCCURRED BECAUSE OF IMPROPER LEANING PROCEDURES DURING A CROSS COUNTRY FLIGHT OR POSSIBLY EXCESSIVE GROUND RUNNING.