SIEG iKC4 Lathe - ATC issues and refit

Update:
I removed the stepper motor and tried moving it unloaded - same problem
SIEG gave me some further tests to put the software in debug mode and disconnecting the motor from the driver - same problem in that the software hangs at the same point

Therefore it looks like a controller fault.

Regards a simple motion controller for rotating an ATC only which might be the best route:
Mach3 demo (since limited code would be required) with a Mach3 card like:
https://www.amazon.co.uk/Motion-Cont...NsaWNrPXRydWU=

or an Arduino controller with some development

.

To me it sounds like the controller is hanging waiting for something to happen (and pretty rubbish programming, in that it locks up rather than timing out).

Are there any sensors on the turret?
And is there anything connected to the Origin terminals on the driver?