Boom. Ordered a board from DiyCNC - out of stock. In comes Mr. Jazz to the rescue, sends me his spare (or next builds board). Realised it was out of stock thursday, Mr Jazz sends Friday, received on saturday and 90% wired on Sunday.

Board works a treat - I still don't know what was wrong with the ZP5A as it is working fine on my other machine (Gekko 203V) but this has dealt with the problem.

Thanks to all that waded in to help - particularly JAZZCNC you bloody legend.