Power steering problem .

The valve sits in a gutter, it can't move sideways much at all. With your "slow" self-steer tendency, you will only need to move the control a tiny bit. Be very careful;if you tap it too hard, the steering wheel can really fly! I'm positive it can break your fingers, perhaps a wrist too. Do not ask your wife to help, she will never let you forget it, and you may be sleeping on the couch for a good long time.
The engine needs to be at a very slow idle.

You can do it with the wheels on the ground, but you could be there for a week pushing back and forth on that stupid pos controller. At least that's what you will be thinking, if not saying.