Always 100 rpm is a bit slow. If you haven't a problem to switch the motor manually on and off, maybe with the front switches, than you can connect the 2 wires directly to the relais, like original. Than you add a 10K rheostat to change the speed from a 10V connector to a outer contact. The slider goes to the +10V connector of the iso-Board. If I come to the machine the next days, I'll make some pics how the switches are connected in original. The CSMIO Board have 2 analog outputs, you need only one for the speed regulation of the motor.
If 16 machines are produced, then they are not so seldom, as I thought, but how much exists today?