I am rebuilding a 1915 Weber Duo-Art upright.  It has gone very well
with one exception: we cannot get the stack to play evenly.  At 6
or 7 inches vacuum, some notes play very loudly and others don't play
at all.  I have tried adjusting pouch clearance with the valve button.
That helps but some valves don't travel to the upper seat and leak.

Making the bleed smaller seems to help but not always.  There just
doesn't seem to be enough atmospheric air in the tracker bar tube to
inflate the pouch.  They work fine at higher vacuum.  If I pull the
tube off the tracker bar, they work very well.

Any thoughts on this?

Joseph Osborne
Carlisle, Pennsylvania, USA