Originally Posted by Robert Rowe

Not that I am aware of, other than a valve re-build (which entails replating the pistons). Usually, the player has been unknowingly compensating for a slight loss of compression. With a larger-cup mpc (i.e. Bach 1), try blowing in the extreme low register -- if you can get a nice, fat F#, the "low compression" situation is tolerable, and not worth the expense and bother of a valve re-build.

My view on this, anyhow.

Robert Rowe