Dear Richard,  You wrote:

> The valves have a Bakelite(?) guide that is threaded into the deck
> and covered with wax, _but_ is also sealed with shellac or hide glue.
> They are so tight they break when I try to turn them out.

May I suggest you get yourself a industrial hot air gun.  You will have
to experiment with the time and amount of heat to play on your stuck
pierces, but "I guarantee you will be successful."  Good luck with the
rest of your project, after you get it apart.

Walter Kehoe
Syosset, New York