[ Philip Jamison wrote in 140701 MMDigest:

> Has anyone ever worked on these instruments?  I can't see any
> screws holding it together.

You should come to all the COAA (Carousel Organ Association of America)
Rallies and spend your evenings in the hospitality area.  Small organ
repairs are a common occurrence.

I think it was at Knoebels last month that an instrument of this sort
was opened up in public.  They are accordions, and are assembled and
disassembled as such.  There are pins at the sides which pull out.
See https://www.youtube.com/watch?v=1G1HgKFrV6c
  and related videos as
a starter.

> Also, some valves seem to be sticking or not working.

You will have easy access to them when you open the ends.

> Can the lead-acid battery be replaced or improved with a more modern
> battery unit?

The batteries in portable MIDI instruments are typically sealed lead
acid battery models used in UPS (computer Uninterruptable Power Supply)
models and/or emergency exit lights.  They are usually readily
available on the Internet and are more-or-less state-of-the-art
batteries.

The Hofbauer 20-key Accordion may be a "Tanzbaer," but I think the
spelling is usually "Tanzbar."

Wallace Venable