In the 130314 MMD Michael Woolf wrote:

    "I'm overhauling my Hofbauer and need to replace the bellows valve
    unit.  I believe it is a USA-made unit and I need the name of the
    supplier."

Two or three decades ago Fischer Organ Company in Erie, Pennsylvania,
was the American agent for Hofbauer.  Paul Fischer sold and serviced a
variety of models and also assembled some 20-note roll-playing organ
kits provided by Hofbauer.  Fischer did not make the organ parts.

Fischer Organ also supplied 20-note electric valve (proprietary MIDI)
organs as part of a gelato franchise scheme.  Many of these were
German-built Hofbauers, some were built by Organ Supply Industries on
contract.

Paul's son continues to run the company's church organ business, but
the firm does not work on crank organs of any sort and would not be
able to supply parts.

If your organ is one of the electronic sort, you might find some
interesting information on my website:
    http://wallace-venable.name/mechanical-music/OSI_Strasse_Orgel 

I might be able to help with information, but parts are not readily
available.

Wallace Venable