Hurco 5m servo errors

Hi, I have purchased an old 3axis 5M hurco CNC which I was assured was working when I collected it (perhaps silly me for not testing).
Once the machine had been started and I try to calibrate the axis it immediately throws up an error for the first axis it tries. Sometimes it's x axis but has also shown the same with y.
The message is just a generic statement; "x axis servo error" as I recall.
So I am assuming it's less likely the servo itself and more the control?
The machine is rated to operate at 60hz but I am using a high end digitally balanced rotary converter (more than powerful enough at 11hp) which is operating at 50hz. Could the frequency difference be causing the servo errors at this stage or is there anything else I could try to investigate the fault further?

The servo drives almost certainly rectify the incoming power before using it, so are very unlikely to care what the frequency is.

Are there any lights on the servo drives which indicate the nature of the fault?

Despite the fact that it shouldn't matter, are you sure you have the three-phase power the correct way round? (If there are any oridnary AC motors, like a coolant pump, do they spin the correct direction?)