PowerSteering

I had a similar problem in my 1969 Dart's power steering gear. When a younger fool, I tried rebuilding it myself to stop a leak. With what I know today, I would have just replaced the sector shaft seal in-car (remove snap-lock and use pressure of running to pop seal out). Twice I put it in the car and it kept self-steering hard. Like you, shifting the valve body didn't center it. I gave up and bought a rebuilt gear which worked. As an older fool, I tried again on my 1965 Dart and got it right. The trick is to turn the input shaft to keep the internal plates all aligned (ccw I recall), until you slide the main unit in and tighten the large threaded ring. If not, the plates can shift and jam out of place. Seems I read that in a manual. One I should have read when younger and more hyper. The instructions in the rebuild kit were sketchy, with tiny diagrams which could barely be resolved. There might be only 2 Edelmann rebuild kits, one for A, B, E bodies until 1972 and one for 1973+ and C-body (all years).