I too, used the existing power supply. It had three different voltages available. Most useful. Similarly to Chris I coupled my 4 wire steppers to the original cabling inside the aluminium stepper covers and then again to my drivers in the control box. The logic is quite simple and straightforward. I am no sparky and was more worried before than after. Just go for it. Think you will find the Isel hardware is well worth preserving.Extremely impressed with the accuracy and repeatability of my 850/1000 machine.