I had a similar problem with my CNC X1 on the X axis. The problem was that the X axis lead screw nut was loose. Since you say you can actually move the table by applying force either toward the column or away from the column there is something loose some where. I would check the nut to make sure it is securely fastened to the base. You should also check the preload on the bearings, if you have bearings on the lead screw. Check the backlash adjustment on the nut as that might be a source of the problem, but I doubt that 3 to 4 mm of movement would be caused by wear in the nut.
John Guenther
John Guenther
'Ye Olde Pen Maker'
Sterling, Virginia