Seek to understand,^Value
I was pounding with the mallet but at that time, the spring was still engaged - so I was fighting the spring.Without the spring or without tension (when the cable is loose), you should be able to push and pull the black piece by hand.
I agree, it goes much more easily without the spring!
This is good information to get my bearings on how the thing works."We", can not adjust it in one place because the spring will always push it out, to the maximum tension
In hindsight, that's what I should have done to loosen the cable tension in the first place!You push it in to loosen the cable just so that you can reassemble it. Then when you let go of the spring, out it goes to full tension.
BTW, in my googles, it seems the Germans use this particular type of window regulator: