I have a 2003 PRT pretty much the way it came out of the factory, no upgrades that I know of. My Z axis doesn't move either in the jog or move mode but the numbers on the screen show that it is "moving" to the new position and they stop moving when it reaches the desired position on the screen. No hint that the actual Z axis trying to move at all, no funny noises, nothing. I am guessing that the driver is probably gone. Any other suggestions?