Hello all,  My next problem with the Otto Accordion repair is that
the main spill regulator sometimes starts oscillating, which makes
a machine-gun-like sound.  It is very unpleasant.  This happens about
one in ten times when starting up or when there is a sudden change
in demand, e.g., when switching from rewind to play.

The regulator consists of a large pneumatic and the moving board faces
downward.  On the moving board is a simple leather covered flap,
hanging down and partially opened by gravity if the machine is off.

When the machine is started, the flap snaps closed by the vacuum.
Then, when the pneumatic closes enough (against spring tension),
the spill flap is forced open as it hits a wood screw inside the
pneumatic.  The Otto Accordion uses a turbine and there is no reservoir
or equaliser.

I have so far tried the following:

1) Added a small spring to the flap to keep it closed when the machine
is off.  It used to suddenly snap closed when turning on the turbine.

2) Added more and less spring tension to the spill pneumatic and thus
changing the vacuum level from 19" to 28" (maximum).

3) Added felt to the wood screw inside the pneumatic to try and make
its contact with the flap softer.

4) Moved the wood screw inside the pneumatic to be further away from
the hinged end of the spill flap.

None of this has eliminated the oscillation 100% and I am out of ideas
at the moment.  Touching the flap or the pneumatic will stop the
oscillation.  It will also stop when the music starts playing.  Opening
the flap manually and then letting it snap shut will re-start the
oscillation.

What is the easiest or best way to dampen a spill regulator like this
to eliminate this kind of oscillation?

Kind regards,

Bernt Damm
Sydney