Andy, Never mind getting them out of the piano -- keep them out of the
house and shop.  I have found a great little device that plugs in a
wall outlet, that emits a frequency that we cannot hear, but the
rodents cannot tolerate.  One drawback is not to use this device if
you have a pet hamster or pet mice.

You should be able to get this device at most hardware outlets for
around twenty dollars, that's here in Canada; bet our neighbours to
south can buy that same thing for half that.

The wonders of the modern age.

Fred Parker