I added that command via the DWC Gcode Console and it worked - worked a treat.
So I then added it to the config.g and re-ran the x homing command and it didn't work - rammed into the side.
Checked what the reply to M574 was and it now says
Endstop configuration: X: low end Z probe, Y: low end active high switch, Z: low end active high switch,
This is good...but it isn't working. with this as the reply to M574 and I run the x homing command it just rams the side - doesn't even hesitate over the homing tab.
I then popped it back into the Gcode console and ran the x axis homing command and now it doesn't work at all - checked the wiring...all good.
What am I doing wrong?