If you don't have any luck getting the old controls to work, you can replace everything down to the stepper motors with something new; it shouldn't cost more than $500 or so if you assemble the system yourself. The current favorite around here is the G-540 from Geckodrives; it will replace the breakout board and drives, so all you need is a heatsink and a 48v power supply set up in an enclosure. Use it with Mach3 or LinuxCNC that you can run on a PC.