Yes it has a stepdown transformer and it has a new MPU and Driver Boards, there is an earth braid attached to the stepdown but sitting loose in the cabinet, looked sus bit didn't know what to do with it as the machine runs fine, other than the dimming. How can I tell if ground wiring has been upgraded?

Brettski... :)

I have seen this before with stepdown transformers, it sounds like the stepdown is not powerful enough to run the machine, or the voltage output of the transformer is too low.