I connected the PC to my old CNC Router and everything works, Z moves up and down NO problem. So I'm sure it's not the p/port RS232 plug. I change the stepper driver with the X driver. Without a change in the Z working right. Checked all connections, everything is tight. I must admit I am at a loss where to look next. If I could get the Z axis to run up & down the way it should I would have a working Joe's EVO. Haven't tried any G-code to see what would happen.