gear box and coupling question

First off, trying to crank the pitman arm takes a lot of power. You are trying to move hydraulic fluid through the box and pump. This is a terrible test.
Secondly, the sector shaft end-play adjustment has to be done in a very specific way.If it is adjusted in any other position but with it centered in the box, it will be too tight.Don't be afraid to run this adjustment a bit loose.
Thirdly, it is far more likely that something else is binding, than the P/S box. There are at least 10 pivots in that system that can cause trouble. The biggest offenders are the lower BJs and a poorly installed idler arm.

So get the wheels off the ground, jackstands or blocks under the lower control arms. Pop the pitman arm loose. Grab the left front tire at 3 and 9, and steer it left and right. It should practically flop over by itself. Do same on passenger side. This side still has the idler arm installed so it will offer more resistance. Take note of the force required. Loosen the idler-arm pinch-bolt and retest. It should now flop over like the first side.
Next pop the idler out of its cradle and let it fall. Then test every tie-rod end.Next test the pivots of the two arms that are attached to the centerlink. All these pivot points should be relatively the same free with no obvious endplays.
Finally, go to the steering box, where the column attaches. Grab the coupler, and rotate it as far as it will go in each direction, there should be 3.5 turns total. It should be easy to turn at all points, but easiest at the furthest from center. If it sticks going through the center, then the sector shaft endplay is too tight. Fix it. If it is hard to turn, no matter what, disconnect the hi-pressure hose from the pump and point it down into a container. Yes the pump will drain so put a pan under it.This is gonna get messy so get used to the idea. Now turn that coupler again; WATCH it!, fluid is gonna come gushing out of that hose, make sure the hose stays in the container. Pump it all out this way, turning the coupler this way and that. Now any resistance in that box, after it is empty, and after you have
properly adjusted the sector-shaft end play,means the box has a problem. And I don't know what it could be. I have rebuilt and modded several boxes, and have never seen one tight.Everything inside there was designed to be easy to turn. The only thing I can imagine to be tight in there is the sector-shaft bearingsBut they are needle rollers, so then that kinda leads me to believe the shaft is bent.If your bearings are in fact tight, the box is no good. But before you condemn it, loosen off all three mounting bolts and try it again one last time. If it is still tight throw it away. Happy hunting,lol,wear eye protection.
Oh, I almost forgot; if you found that when you loosened the idler arm pinch-bolt, it got easy to turn the passenger wheel, then there is an issue there.It could be one of two things; a) the spacer sleeve is too tight in its bore, or 2) it is too short, and the pinch-bolt is clamping more than just the sleeve. Find out which it is and correct it. It should offer some resistance to turning, but not much, and no play.

I worked nearly six years as an alignment tec. I have seen a lot of tight BJs do this. When the BJ gets tight, the Chrysler over-boosted box does it's thing really well. To correct the direction that car is travelling in, you turn the steering wheel. But the wheels don't steer right away, cuz the Bj is tight. So you steer a bit more.This causes the box to apply boost, and then the joint finally breaks free, the tire turns and immediately the Box senses it and relaxes the boost. In the mean time the tire has steered too far, and at 30mph you are traveling at 44 feet per second, so almost immediately you have to steer the other way. This sux big time. You are constantly sawing on the wheel. I tight idler arm will do this too, but I didn't see that very often; it was mostly BJs.
BTW this problem was not limited to any particular brand of car or joint.The offshore stuff seemed to do this more often when new, but in just a few hours they relaxed and in a few more hours they were loose and in a few more hours I had to replace them with better junk.I fought my employer many times over installing that offshore junk.
That was 20 years ago. At that time Moog and TRW/Federal were the good stuff. Now I hear they might not even be the better junk. I never saw problems in Moog uppers. But I live in a small community, with a customer-base of perhaps as many 30,000.
So again,happy hunting