Bridgeport BOSS 6 Spindle Problem

The spindle on my BOSS 6 won't start. I have traced the problem back
through CR3 and the SCA board to signal #203 which leads to a
terminal block in the power cabinet, a terminal block in the control
cabinet, to K6 on the ZDI board, and then to an opto isolator. Anyone
have a schematic of the ZDI board?

~petev