Hi,  I removed the tracker bar en started cleaning it.

My observations :

1.  I guess the first and last four holes, situated right below the
expression holes, are not used and as such not connected to anything.
There are only 80 bellows on my Stecks stack anyway.  Or are they
connected to "something" else that operates when the piano is not
switched in Duo-Art (DA) mode and the 8 expression holes are not being
used?

On Peter Coggins tubing diagram for a Stroud DA these eight notes
_are_ connected and do_ play when not in DA mode.  So his piano
apparently has 88 striker pneumatics and not just 80 like mine.
http://www.geocities.com/Heartland/Ranch/9374/stroud/diagram.html

2.  The ninth hole is not rectangular like all the others, but is
round.  Any special reason?

3.  What is the function of the other holes on both extremities of the
tracker bar?  (Must be for things like automatic shut-off, reroll etc.)

I'd be grateful for any comment or advice.

Best regards,

Patrick Boeckstijns