[Dobie Gillis]

Sounds like a minor box adjustment may be in order, but I would still check the linkage downstream of the box first. Pay attention especially to the the ball stud that connects the Pitman arm to the drag link. They're often neglected and the stud can become egg shaped, causing play. Ball stud kits are available from the usual suspects. There is a procedure to be followed when adjusting the box. The 1st step is to make sure the wheels are pointed straight ahead, then, with the wheels off the ground, adjust the screw in small increments until some drag is felt, then back off until the drag is just eliminated.