Jack, is there not a spring (#18 in VB pp86) in the H1?
One area to check for a vacuum leak that is often overlooked, is between the manifold and block where the "locating ring" fits. There is a gap in the ring that has given me a problem or two in the past! One way to find a vacuum leak is to use a propane torch, unlit, around suspect areas. If an increase in RPM is noted while applying gas, you can pin-point a vacuum leak!! Goes without saying...NO SMOKING!!