Re: Jerky motion in all axes...
I have seen identical problem, (not on an X4. It was a custom machine), that was traced to a driver (leadshine) that was faulting,
and reflecting spikes back through the system.
All the while, opto isolation still in use masked the issue. Inductively coupled spikes from power cables were the cause.
A new driver, or not using the bad axis made the problems disappear.
Super X3. 3600rpm. Sheridan 6"x24" Lathe + more. Three ways to fix things: The right way, the other way, and maybe your way, which is possibly a faster wrong way.