The Paperface BI-DIRECTIONAL ROUTER is three switches which route one input to either of the two outputs or either of two inputs to one output according to a pulse or control voltage level.
Adjust each trim pot on the back of the module until you get +7V and -7V on the appropriate sides as labeled on the PCB. There are 2 test points on each section for use with a multimeter. It is best if you have all IC's uninstalled while calibrating the voltages. Then install the IC's and adjust the voltages as needed.