Sounds like the gib was loose and is now jammed. The gib is a wedge that is used to adjust the fit of the table to the mill saddle. Check the manual for location. Basically, you'll want to back out the screws on both ends, locate the small end of the gib and push it back inside the table with a punch. shouldn't take too much force to do. Once it's loose again, adjust it until you just feel a difference when moving the table, and then snug the screws at either end of the gib. Do not tighten them hard!