As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CYLINDER EXHAUST SEAT NOT SEATED INTO MACHINED PORTION OF CYLINDER HEAD ALL THE WAY IN. SUSPECT CAUSE: UPON INSTALLATION AT FACTORY, SEATS ARE NOT TAPPED IN, BUT DROPPED IN ASSUMING INSTALLED. SUBMITTER STATED ALWAYS INSPECT NEW CYLINDERS FOR GOOD SEATING OF SEAT INTO CYLINDER.