A recent eBay listing of a Duo-Art grand spoolbox and upper action
parts (item number: 170102639408) reminded me of some questions
I have had about the later model Duo-Art actions where the tubes
from the tracker bar go around the edges of the keyboard.

Were there many variations in these Duo-Arts?  I have a Weber grand
with all the controls in the spool box.  Mine has the usual three,
double acting pneumatic wind motor.  The one on eBay seems to have
a 5-pneumatic single acting motor.  It also has only one lever to
control the intensities.  The lever moves a rotating valve behind
the red felt circle at the left which I assume controls the theme
intensities.  There are two buttons which I assume accent either bass
or treble with the theme intensity.  Is the accompaniment intensity
just set to some middle value or was the theme intensity set to one
step above the accompaniment, or what?

My Weber has two of the rotating intensity valves and two levers,
one for Accompaniment, one for Theme, but it has no buttons.  I don't
find any way of accenting a note.  Did the theme level only work on
Themodist type rolls with snake bites?  Under the soundboard mine has
the traditional accordion pneumatics, not the fan-style regulator.

Both the eBay and my instrument have the "floating" trackerbar where
the bar, instead of the spool, shifts right and left, and they both
have the wind motor governor above the motor.  Both also have a feature
where moving the Tempo lever to zero (or minimum speed) turns off the
electric pump motor.  What was the purpose of this?  Did they worry
that someone might use Tempo zero as "off" and leave the motor going?

Are there other variations along these lines?  Did one version precede
another or was the customer offered different options?  Any theories?

David Sharpe
Western Massachusetts