Maybe the actions I describe are still not quite specific. The clutch travel feels very short and with more pressure than usual. Believe me, I am familiar with clutch feel and this pedal does not travel far enough to disengage the clutch. The shift lever moves freely yet does not try to engage any gear.
Now if the clutch pedal is in the "engaged" position you would figure that some transmission noise, such as rotation, would be heard. And if trying to engage a gear in this situation, then that bad sound of gringing metal would ring in my ears - nada!
I agree this is a strange one. I will check the vacuum shutdown but I believe the clutch linkage is not a factor.
I am going to try and contact the prior driver to see what the symptoms were when it quit being a "normal" MB.