Hi -- I tried a heat gun to remove glue from pneumatics that were so
heavily coated with PVC-E that you could not see the wood underneath.
With all due respect to Art Reblitz's solution, all I can say is,
"Been there, done that."  A heat gun is too dangerous and can easily
scorch the wood.  It will also ruin anything else in its path.  It
should work but it needs to be controlled very carefully.

I eventually used a hot plate on the pneumatics, but this is not
a good solution either because if he could place the valves on
a hot-plate, he wouldn't need the solution.

I recommended trying an iron: set the temperature low enough so that
the glue is softened but not high enough to start scorching the wood.

Eli Shahar