Regarding A. B. Bonds comments on burnt shellac --

I don't burn it.  I put about two cups of yellow, cheap hardware-store
shellac in a large shallow disposable pie pan and let it evaporate in an
open, ventilated area, stirring once and a while.  After a while, it
thickens up to about 1/4 cup of "thin molasses" consistency, and I put it
in a baby food jar.  It lasts a *long* time!  And, there's not much to
clean up!

While "burnt" or "ultra-thick" shellac is a bit messy to use, it seals
like nothing else, and it makes future repairs very easy.  I use it
wherever such shellac was originally used in a piano's player mechanism
if at all possible.

Patrick Mullarky