73 /6 PS: Correct way to purge air from box?

Thanks for this guys. I conducted this last weekend and while it improved the center, its still slightly off and to the right. I loosened and tapped and it appeared to not move any further. I loosened a little more and that was a mistake. It sprayed fluid out from under the valve, so I quickly had to tighten. Now the best I can get is it slightly turning right.

Is this the only adjustment?