Hi Bob,  I rebuilt one several years ago.  I do have some tubing left
over, but not enough for the project.  I think I got it from PPCo as
a special order.

There was no gasket between the plates.  They should provide an airtight
seal if not damaged.  A word of caution: do not 'over-tighten' the brass
plates.

I hope this helps.
Roger Jennison - Roger's Piano Service
http://www.rogerspianoservice.com/