Hello MMD.  Having posed the query: "Would it be reasonable to use
burnt shellac to fix the dowels on the upper ends of the brass pushrods
in an Aeolian action", and having had a couple of responses that said:
"Yes, that should work", I went ahead and tried it.  I can report that
the shellac certainly fixed them.  Within a couple of hours those dowels
were as tight as -- well, the only simile that immediately comes to
mind involves the conclusion to a porcine alimentary tract, so I'll
move on.

I endeavoured to preserve the positions of the already carefully set
up dowels by putting a small spring-loaded clamp onto the brass rod,
immediately underneath the base of the dowel.  The clamp was made to
protect small electronic components when they are being soldered onto
a printed circuit board.  The clamp worked reasonably well, except when
I either forgot to put it on (about three times), or when it sproinged
off for no obvious reason (about twice).  However, when I replaced the
upper action into the piano, I found that about a dozen dowels were
misplaced.  But the shellac had really cemented them in place.

I got out my 70-watt electric soldering iron (purchased about fifty
years ago) and wrapped bits of aluminium foil around the appropriate
pushrods, so that they would be protected from unwanted solder or
scratches, and applied the iron, just underneath the dowel.  After
about twenty seconds the shellac had softened and it was easy to adjust
the dowel.

I think I had better leave a note attached to the player action,
warning the next rebuilder about that shellac.

John Phillips in Hobart, Tasmania