Question Wurlitzer 1400

I was fortunate enough to obtain an "Automatic Level Control" which was
optional equipment for the 1400/1450. Can anyone tell me the function
of the "Chassis Switch" and how it should be hooked up? On the ALC it
is a small 4 pin socket with two pins being unused inside the unit. It
is pictured on page 14 in the service manual, but I can't find any other
information on it except the 8 pin main connector where it is plugged
into the amp/power supply is shown on the amp schematic.

Thanks for any help.

Bill