the way that box works, there HAS to be play in it with the engine NOT running.
That first couple of inches, activates the assist mechanism . If you adjust it out, you will have immediate boost all the time and the car will be all over the road as you constantly make corrections.
If you tighten the sector shaft too much, it will stick on center. Then you will move the steering wheel, but the resistance of the sticking will call for boost, and Pow! you will get it, and again be chasing the car all over the road.
The proper way to not get excessive boost is to increase the resistance of the reaction springs inside the box. You add more of them to dull it. This simultaneously gets rid of some of the play.
To see how the box works; open the hood, with the engine off, and rotate the steering coupler. Watch the coupler. It will move out of the box, on either side of center. That is how it works and it is normal. When the car is driving, that action calls for the boost. When the engine is running but the car is stopped, that action is what gives you extra boost for parallel parking, and similar slow-speed maneuvers..