I was backing up my boat trailer today and for the last year or so when backing up the part that the ball on the vehicle connects to jambs up. Normally I can pull forward and hit the brakes on the truck and it will come back down but tonight it took forever to get it unhooked. I noticed the nut on it was a little loose so I tried tighting the nut but it just spins. It does not loosen or tighten. Is it supposed to be that way?