I 'm following the discussion about the screws; it's nice to see
everybody's ideas.  But did you ever think of electricity?  I do.
Almost every screw -- big ones, very small ones -- no problem,
I get them out of the wood or metal.

There are special electric tools (DC 1.5 volt 80 Amp.) for the
shoe repairman to get an iron nail out of the heel of a woman's
shoe.  It's simple with electricity.  In a few seconds the screw
will be so hot that it burns itself lose without only a very
little, little, little wood damage inside.

Your varnish, wax or other stuff will not get in touch with it.
For the big screws of 2 up to 4 inches, I have a bigger electric
tool in DC, 2 volt 110 Amp.

Wow, that helps a lot!  In 15 to 30 seconds and it is out of it.
If you need a photo of it how it works, ask me.

Louis Huivenaar, Pipe organ builder and restorer
Netherlands
Appraiser under Oath for Harmoniums and Reed organs in Europe
http://www.harmonium.com/