Dennis there are a host of drives out there that will run your servos. BUT they are NOT the DIY type. Your servos are TOO large for most of the low end DIY drives that were designed around small/cheaper servo setups.
SOmetimes if you are going to play big to have to spend big.(;-)
I was in the same boat when I started my project. I soon realized that at the level I wanted to play in I had to have very dependable drives.
I did a quick search for your application and there are plenty of options out there. You just have to know what you are looking for and be able to commit the $$$$$. I also came across some vendors that offered replacement drives for some of the older machines.
BUT before I would spend the money in your case I would make absolutley SURE that your drives are dead. It still could be something relatively simple. If you are certain that you are going to strip it down and start fresh, then strip out all the unneccesary hardware and hook the drives back up in a simple MODE (power supply, drives and servos) and retest the drives again without all the old gizmos interfaced to them.
Keep it simple (;-) TP