I would like to offer a test and possible restoration tip for old
finishes.  I have found that denatured alcohol can be used to not only
test the nature of old finishes, but is also a very helpful restoration
tool.  I would never recommend using a commercial paint stripper on an
old instrument without first giving it an "alcohol test".

Just put some denatured alcohol in a spray bottle, and spray a wet
coat on to a test piece.  If the finish seems to lose it's crackley
appearance, even if there appears to be a top layer of 'stuff', it
is probably a shellac base. The old final coat will skim off as some
sort of crud.  This is a sticky and messy process, but well worth the
effort.

If your test piece gets sticky and the finish flows a bit, add some
more alcohol and use a cabinet scraper to remove a small area of
finish. Spray a little more alcohol to keep it fluid.  If that works,
then you can strip the whole piece with alcohol, which has the great
advantage that the original grain filler and stain will remain -- a
very messy process!  Precede it with a good cleaning of the surfaces
with a strong detergent (I use Oil Eater) and soft brush, with a quick
rinse and wipe with old towels, followed by drying in a warm place out
of the sun (this gets rid of all of the dirt and grime).

I have managed to preserve the original fall board and other decals
on my Wurlitzer B orchestrion and Seeburg F by using the above method.
It just takes careful masking and attention to detail.  Shellac is
a wonderful material and is still prized as the best primer for any
other finish.  I always use two coats of shellac to prime new wood
surfaces.  If the nitrocellulose lacquer top coats eventually craze,
then the finish can always be removed down to the shellac layer with
alcohol and restored.

Common sense suggests doing this in a well ventilated area with no
flames.

Larry Emmons