Thanks for the informative replies.
You both made a very good point about the ageing hardware.

Look like I will concentrate on finding a machine in decent mechanical condition for the right price and budget in enough for a hardware upgrade.

Had a look at the CSlabs web site I see you can get a 6 axis controller for around £500.

What size AC servo would you recommend looking for?

I guess if I wait long enough a good machine will come up with a hardware fault.

Cheers Dave