I have worked on a couple of these, one of which is mine, and the
problem is not necessarily a leak.  Be sure when you push the lever to
"Play" that the vacuum shutoff for the stack is opening and is allowing
proper air flow from the chest.  Also check to see that all of the
large hoses from the vacuum chest are in good shape and connected
properly.  Also check the springs on the back of the two foot bellows,
and the leather flap attached to the back of the foot bellows.

If all is good so far, then go to the plastic valves, behind the bottom
board.  For the most part, they have always been okay for me, but if
one has the bleed stopped up and the air is not venting through the
bleed, the valve will remain between open and closed and an air leak
would he heard from the top of the valve.

To clean the bleeds, get a small piece of hose that fits the nipple of
the valve.  Remove one hose from a valve and put your little piece of
hose on the valve and suck out the "trash".  Before putting the tracker
bar hose back on the valve, blow through it and see if "trash" comes
out the tracker bar opening.  Put this hose back on the valve and move
on to the next one.  These little valves are a pain sometimes but
they're easily replaced.

I know that may not seem like fun, but, but when you get it going, the
notes will be sound stronger.  Hope this helps.

Robbie Jacob
Newport News, Virginia