Thank you for your reply.
Could be a huge bonus having you help if you have loads of grounding experience, as that could be the first starting point.
The following might help
I am in contacted with a chap over in Australia (Im Based in the UK by the way), who also bought one of these machines (by the way, its not a new setup I have made, its an actual CNC bought from a Chinese supplier). I believe the machines are based around the mechanics of the old Makini CNC but with revamped motors, drivers and electronics (apparently!)
Anyway, this other chap has been having issue of a different kind, but possibly all down to the same design problem.
He was finding an issue with the spindle drive that would cause sporadic operation on the spindle speed at low RPM. He found that the problem with the spindle drive was cross talk between the output and input of the axis stepper motor drivers, they were sending noise back into the transformer, then into the motion board and on into the spindle driver.
Best I be honest up front, I am from an electrical engineer (Im a mechanical grease monkey). So if you could share any help and steps in baby talk.....that would be great. But it sounds like this could be a good starting point if you all agree.
Therefore, what do I need to look at doing? Do I need to separate components, separate wires, fit ferrites, etc ??
Thanks again all