Not sure why your parallel port is not working as it should - certainly DXF0 is the correct address to use if that's what it reports in device manager.
- Is it possible to hard wire the Slave Axis (A) with X? This could free up a stepper port on the Gecko G540?
Not a good idea. It sort of works but the modern driver controller chips sense back emf in order to circumvent mid-band resonance stalling and they get confused when given the info from two motors. If you want to try it then check with Gecko first, I am sure they will give you a similar answer.
Tweakie.