As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) INTERMITTENTLY ENGINE WOULD RUN ROUGH - CYLINDER LOW COMPRESSION. FOUND ONE OF THE LOCKS OUT OF POSITION RESULTING IN VALVE SEAT EXTENDING HIGHER AND RESULTING IN POSSIBLE CONTACT WITH ROCKER ARM. ROCKER ARM NO SIGNS OF DAMAGE NOTED. CYLINDER REPLACED WITH REPAIRED UNIT.