Phil Duclos mentioned clamping diodes and the unlikeliness of finding
them on an older instrument.  We have added diodes to our 1928 Reuter.
That parts aren't expensive -- I think the price per diode was something
like 39 cents.  (Notice that us really _cheap_ guys know how to get the
cents sign on our computers :)  However there was a lot of labor
involved, all volunteer fortunately.

Unfortunately we found out the organ had been reverse polarized by
some unknown repair person eons ago, and when we later added some solid
state switching we had to reverse the polarity and remove the diodes!
Fortunately the solid state switches included their own clamping diodes.

Back to the original subject; the addition of the clamping diodes was
to extend the life of the key contacts and it is probably a recommended
addition to any similar installation.

David Dewey