Anatomy of a WurliTzer Theatre Pipe Organ
Accomp relay has the back board re-installed. The original graffiti
is usually hidden.
This must be done before the primary box is attached because of the
screws at each which end up behind the primary box.
You can see the row of screws at the top and bottom which attach
the back to the chest.
The light area of wood is where the primary box covers the back and the
rows of screw holes at the top and bottom of this area are where the
screws come through from the other side to hold the primary box.
The row of holes near the bottom of this area are the channels
to connect the relay secondary pneumatics, on the other side, to
the valves in the primary box. Note these holes are in one line on this
side but in three lines on the other side.
The other three rows of (empty) countersunk holes hold the three
trays of relay pneumatics to the other side. One row is inside
the primary box, but they can be accessed between the valves and magnets.