Peter,
You were spot on regarding the linkage to the PCV valve. Sealed the pushrod tubes externally with a light application of JB Weld. Checked the PCV and it appears to be incomplete and cannibalized. Internally the valve has a set of four prongs that appear to guide a small pin which rests on the one way valve in the lower portion of the valve. In the servicable (upper) portion of the assembly I have only the pin, a spring and diaphragm (which I have replaced). In that configuration, when the engine is running there is no suction to the valve cover as the small pin blocks the valve. I removed the pin and readjusted the carbs to compensate for the additional airflow into the manifold, and all runs well and the motor no longer leaks. However, I instinctively feel this is still not right as there is a constant vacuum pull on the valve cover outlet now.
Do you have a picture or know of a detailed schematic that shows all servicable parts of the valve? TIA.
Regards,
Dan