As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING ROUTINE COMPRESSION TEST FOUND NR 3 CYL COMPRESSION LOW. REMOVED CYLINDER AND FOUND THE INTAKE VALVE SEAT HAD BEEN INSTALLED AND GROUND CROOKED AT THE FACTORY. SEAT WAS REINSTALLED AND GROUND CORRECTLY AND CYL REINSTALLED ON ENGINE.