I have a Steinway Duo-Art upright with a steamboat pump.  There are
pictures, I believe, in the MMD Archives of another one.  My motor
is mounted on a board that has a leather strap on the back side that
fits over two metal pins on the left and two on the right.

In the front, there is a thin (about an inch wide that runs
perpendicular from the board to the floor and from the board-on the
right side, another that mounds from the board to a metal arm metal
bracket that has a 90 degree bend at the top so it looks like an
upside-down "L".  This is mounted to the block on the right side of
the case.

I had mountains of trouble with this until I discovered there are two
screw type holes in the motor floor board.  One is in the middle in the
front, and one in the middle of the back.  The motor was never even and
I had a lot of trouble and in fact burned it out.

The motor was too heavy for this leather sling.  I finally went to the
hardware store and bought two coil springs and placed one under each of
the screw holes in the motor mount board.  It has worked like a charm
ever since.

Every one of these that I have seen (and it is only a handful) have
trouble with this leather sling arrangement.  The coil springs made a
dramatic difference.  No vibrations and the instrument is much quieter
when playing.

If you look at the pictures in the Archives, look at the floor board of
the motor.  One coil spring under each of the screw holes in the motor
floor board and it will work.

Randy Hammond