After homing all is fine, when printing the Z-axis stops advancing
Awesome, I got it fixed!

I've restored to default the Firmware EEPROM Settings in the driver program and it's all fine now. I have no idea how that got changed as I would never go mess around there.

I CAN PRINT AGAIN!!

The program I'm using is Repetier. It has a Firmware configuration setting under the printer settings. The values in there was a bit odd so I took a chance and pressed the Reset to Factory Settings and it worked. There is no version number attached to the setting