Further to the posting by Cecil Grace [040311 MMDigest], worm-eaten
wood can indeed be a problem.  When faced with this bug in the past,
I have resorted to a quick, cheap and easy method of adding "New
Strength" to old and fragile timbers: "P.V.A."

My answer is to take a syringe with a course needle, and to inject
a rather diluted medium into the flight holes; the tinder dry wood
accepts it readily.  I then inject a slightly thicker, but still
diluted medium.  When completely dry, the difference can be
substantial.

A cautionary note: as with all such tips, please experiment first.
A piece of scrap heavily-wormed timber should be opened to expose
the beetles labyrinths; the correct dilution can then be gauged on
the absorbency factor.  Ideally the solution will run readily and
penetrate remaining material.  Good Luck.

Mark Singleton