Lead screw movement deviating from center by more than 3mm or 1/8" (midline to peak)
Resolution:
Slightly loosen the two M5-25mm mounting screws holding the block, by 1/4 turn, which should help better align the lead screw with the other components.
Re-assemble the ACME nut and coupler by pulling the lead screw, which should apply more tension and straighten out the wobble. The technique is outlined in these assembly steps for the Y-axis and X-axis.
If the above do not help, check if the lead screw is bent. Remove the screw and roll it along a surface that is very flat to see if it rolls evenly.