Hello... Thanks a lot for your useful videos. I have a similar problem.. When I turn the steering right it shakes left and right although the filters and the seals of the piston are new. When I close the hydraulic lines going to the piston the steering runs smoothly.
you may check this video. the steering wheel vibration is also coming from the steering pump, check the relief valve of the steering pump. czcams.com/video/tart18CbRT0/video.html
We do understand.