Have you looked at Mach 3 or Mach 4? Mach 3 is what I use on all my machines except the newest lathe. It runs my plasma table. I am not an electronics guy though. I do recognize some of the parts, but the BOB or controller panel is probably what went out. You would need a new computer, a Break out board, some wiring and consider Mach 4. It is the newest and probably will be supported for a long time. Mach 3 is no longer supported. Since you have most of the hardware, I think you can get it going again relatively cheap. $1000 or $1500 would be considered cheap.
Some other electronics or servo guys will have to chime in. I am not a lot of help with either of those.
Good luck with it.