Been there, done it.  Considering the condition of the tubing, it is
going to be more than an all-day job to remove the action, since all
the tubing will most likely need to be replaced.  If you need copies of
the tubing diagram and maintenance book, I can help.

To remove the action, you must first remove the tracker bar and related
parts.  All tubing can be removed intact by removing the screws holding
the manifold blocks together (those that pass through the keyboard.)
You will also need to disconnect the various regulating levers (speed,
volume, etc.). and the usual things you've got to remove to take out a
grand action.

Once all of this is out of the way, the action will slide straight out,
being careful not to break any of the hammers.  (Done that too!)

Since the tubing is all original, it will need to be replaced.  It
makes no sense to go through all the effort of removing the action and
then not replace the tubing.  Order gobs, you'll need it.

Jim Quashnock