PG ,
I have made the balance at the PS control valve. I did a short ride to check the thing...
Now it seems that the effort to turn the steering wheel left-right is the same. far better than before but still not perfect when I turn left ( less precise than right). when I turn left in bends at 30-40mph , I have still to make some corrections. I think I have to check and tighten the steering gear box, since I have still excessive lash, in my opinion. Unfortunately I can't send my gear box out for a rebuilt ( too expensive) . So i have to live with it...