As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
NR 3 CYLINDER EXHAUST VALVE STUCK AT 300.1 HRS. NR 2 CYLINDER EXHAUST VALVE STUCK AT 351.1 HRS. REMOVED NR 1 AND NR 4 FOR EVALUATION, CYLINDER SHOP FOUND PROBLEMS WITH THERE EXHAUST VALVES. THESE WERE NEW SUPERIOR MILLENNIUM CYLINDER ASSEMBLIES INSTALLED AT ENGINE OVERHAUL 351.0 TSMOH. (K)