Hi again,  In connection with John Johns' problem, why not just tee
the Soft switch into the line from the tracker bar for the hammer rail.
It will then work and won't influence the operation from the tracker
bar.  See how it performs, and if it does not, make a pallet valve for
the hammer rail pneumatic and tee that into the no. 2 accompaniment
pneumatic.  That is then pretty much how many originals were done.

If you then one day make the missing lever, all you have to do is
remove the one tee and connect the tracker bar to the shifter
pneumatic.  Your Soft switch will still operate then as intended.

Regards,

Bernt Damm
Cape Town