Some time ago I rebuilt a 65-note Pianola pushup, built circa 1901,
of the original design with pneumatics mounted vertically.  This had
the pneumatics glued directly to the boards, but the pneumatic boards
themselves were screwed and gasketed to the base board containing the
windways.  I'm sure I've been told that the even-earlier instruments
were totally glued together.

I am currently rebuilding the stack of my 65-88 note Gotha Steck
Pianola grand.  This is obviously a very early design of grand stack,
and indeed I have found imprinted in the varnish of one part of its
innards newsprint saying (in mirror image) that "everything must be
sold by December 1908", priced in dollars, which fairly firmly dates
and places its construction!  (The extended-case grand, and the 88-note
scale, were both 1908 introductions for Aeolian.)  This stack has never
been rebuilt, indeed has probably never even been dismantled, and its
pneumatics are glued on with pouch leather intermediates.  They are
still firmly mounted but come off easily and cleanly.  Incidentally,
the rubber cloth is still in beautiful supple condition, and has only
given way on the middle notes thanks to sheer wear.  Built-in
obsolescence was not an Aeolian trait!

With regards to whether Aeolian's intention was serviceability, it only
takes a fairly cursory comparison of stack and piano serial numbers in
the UK to spot that they don't line up particularly well.  Some of this
is probably due to batch-production where completed parts sat on the
shelf for some time before use, and some is due to later completion of
German pianos left unfinished during WW1 - this work was primarily done
to research Gotha Steck production.  It's obvious that some pianos have
newer stacks than they ought to, but frequently much older wind motors.

I think that interviews with Aeolian employees established that the
policy when something failed was to replace it with one from the factory
(from the batch sitting on the shelf).  The original parts were returned,
and it's clear that at least wind motors were refurbished and used in
new installations.  So, some consideration was made of serviceability,
but whether this extended to rebuilding stacks has to be a moot point.

Julian Dyer