In early instruments, Wurlitzer glued the hoses into the tracker bar
mounting block, using either thick shellac or hot glue -- I don't
remember which.

I've restored several of these by gluing the new neoprene into the
wood with thick shellac.  In the instruments where I've done this, the
neoprene was a good snug fit.  This was only a coincidence, as there
is no guarantee that the O.D. of any modern tubing will happen to be
the same as the original.

In later instruments, Wurlitzer installed brass nipples in both the
block and pouch board or connecting manifold.  I've converted several
to the later style by drilling the holes in the block out for maple
dowels, gluing dowels in place, and redrilling for brass nipples to be
sealed in place with thick shellac.  This makes for easier servicing in
the event that a tube has to be removed later.

Incidentally, I've stopped using the term "burnt shellac." I started
this in the first edition of my piano servicing book after I heard the
term used by Bill Singleton.  Since then, I never burn the alcohol out
of premixed shellac.  Instead, I use shellac flakes & alcohol to create
a very thick mixture.

Best regards,

Art Reblitz