Had a problem a few months back, noticed my zj pitman arm was rocking side to side on my stock xj box . I went ahead and bought a new one and installed it. To get the arm tight i have to use two lock washers so the nut doesn't bottom out before the arm gets tight.

Was good for a bit and now the new arm is loose again giving me excessive play in the wheel. Is this a common issue? Is the sector shaft tapered? Swap the box ?