My mom was mowing and got a large rock caught between the mower deck and the left front wheel. After removing the rock the deck is running off to the left side, far enough to cause the right front deck roller to hit the back of the right front tire. I can't tell what is causing it, the arm from the tractor to the front of the deck seems to want to come out of the bracket at the deck end. It didn't do this till the rock so something is tweaked but I can't see what it is, anybody had this problem before?