Thanks. I found a bit earlier today that under the CS LABS plugin you can select 'ignore limits whilst homing', so that's worked. Had to fix one input that was set for the opposite side.

Can I just say what a dog Mach 4 is. Using Centroid now on all my other machines, stable, easy, lovely. Mach 4 is inconsistent, doesnt do as you would expect etc. Cant wait to ditch it.