When you have the steering shaft with valves installed on shaft, turn the valve bodies so you can see the plungers in the holes on the side. Wrap the lower end of shaft in a heavy rag and put it in a vise in the horizontal position. grab upper valve body in one hand and the lower valve body in the other. push both valve bodies together and slide them slowly back and forth wile looking at the plungers. You need to be able to feel a "neutral" where you can move the valve bodies a small amount without the plungers moving. If you can't, you need to add shims until a neutral is obtained. If the neutral is too big(more than about .010") you can remove shims to get it to .010" or less. It is better to have too much neutral than not enough. I hope that makes sense. It is difficult to explain without demonstrating it.