Bert, I agree, this is the major issue. And it should be solved easily by changing the in the meantime identified bad shaft.
The smaller second issue is that the steering rack itself was adjusted way to hard. The rack and pinion itself is ok without any wear but it was almost all the way turned in during the 5.5 years of the cars lifetime. Therefore the spring below the screw may be pressed too much because I do not feel a smooth change of resistance but a relatively abrupt change at ca. 1/8 turn out of the pinion adjustment screw. And unlike in Dave’s case who described 9 years ago in his old TM thread that it was very hard to set the adjustment screw in, which follows the spring, the adjustment screw following „our“ spring can be turned into it‘s thread without the need of any power. So could it be possible that our spring was pressed too much and too long time and is consequently out of shape? Or keeps such a spring shape and elasticity once released?
All that saying I think when using a spring which is stronger I could fine tune the steering resistance in smaller steps.