As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WHILE IN CRUISE FLIGHT, ENGINE WOULD ONLY DEVELOP APPROXIMATELY 1300 PRM. AIRCRAFT MADE PRECAUTIONARY LANDING. INVESTIGATION SHOWED BOTH ROCKER ARMS BROKEN CYLINDER NR 2. EXHAUST ROCKER SHOWED EVIDENCE OF BEING CRACKED FOR LONG PERIODS OF TIME. BELIEVED THAT EXHAUST ROCKER BROKE AND LOOSE PIECE JAMMED INTAKE VALVE CAUSING INTAKE ROCKER TO FAIL. SUBMITTER RECOMMENDS FREQUENT CLOSE INSPECTION OF ARMS.