Actually, I was aware of that tension spring, but forgot to mention it in the original post here.

My fix is for "damaged" drives, not just ones that need a bit of adjustment. If somebody has lifted the upper head far enough to permanently bend the hinge, chances are that they have also stretched that little tension spring. In my case, moving the spring to the tightest option did not help. It is most likely designed to adjust only enough to compensate for minor wear.

Apart from the likelihood of damage to the tension spring, there is also the problem that the spring is attached very close to the hinge and therefore exerts very little leverage. It can't apply enough force to overcome the extra 10 degrees flex angle caused by distortion of the hinge, which is quite stiff. It might work if the hinge has been bent only a very few degrees and the spring not stretched.

My spring clip applies its force further from the hinge, and therefore with many times the leverage on the hinge.

It's not beautiful, but it works for me.

Rick