Quote Originally Posted by Jonathan View Post
If that's the only problem it implies the direction setting for Z in mach 3 is set the wrong way. Could try going to "Config"->"Ports & Pins"->"Motor Outputs" then changing "Dir LowActive" on the line for Z. However if it's working fine in another place that's not going to help you. The only things that can change the motor direction is the state of the direction pin on the stepper driver, or changing the polarity of either phase. The latter surely cannot happen, so I'd put a voltmeter on the Z-axis driver direction pin and see if it looks right.

Whereabouts are you in Nottingham? I'm at University of Nottingham so if you don't get it sorted today I'm happy to come and have a look as it shouldn't be far?
Sorry i missed your offer to come and sort us out Jonathan, lol, much appreciated mate!

At the moment we are able to run ok on approx 50% of the bed without problems which enables us to continue and produce parts (for the moment anyway!)

In the meantime I will make up a new cable if i can work out what the connectors are!