XY shifting problem

[wackyvorlon]

That looks like a slightly bent leadscrew. As the screw rotates, it causes the table to wobble. I'll wager the pattern of bumps lines up well with the threads.

[3dkarma]

That looks like a slightly bent leadscrew. As the screw rotates, it causes the table to wobble. I'll wager the pattern of bumps lines up well with the threads.

It does look like this. This can be exacerbated if both ends of the lead screws are fixed. One end needs to be free or the bend in the lead screw will translate to movement in the axis.