Thanks for the info guys.
Yes this afternoon I dropped off the cylinder head and the rings are free with no carbon anywhere.
Spark plug has that perfect tan color.
I am using regular Steel (sp) oil mixed 40-1.
I flushed everything out with a gas hose from electric pump and reassembled and squirted with soapy water looking for bubbles around fins and spark plug.
Nothing...... with lose of compression at TDC.

Beats me as this motor has never had a prop broken and always had high compression.
Always flown off a grass runway and minimum dirt exposure.
Is mounted on a Hanger Nine Pawnee with plenty of airflow.