Box bottoming out
You MAY be able to adjust that out with the toe adjustment (Tie rod ends), and then recenter the wheel with the steering arm drag link adjuster. MAYBE. OR, if it only does it one side, SOMETIMES you can loosen the steering shaft off of the gear box, turn the box back in one turn, reattach the steering, and then straighten your wheel from there. It depends on how much travel is left in the linkage when the box hits it's limit.