My friend:
I feel sorry for you but I am stuck with the same problem.
I just change my trailing arm yesterday and I was not able to remove properly the old cable but since I was replacing the arm and the new arm came with a cable on it I just cut out the old one. At the time to insert the new cable on compensating lever I did like you, including reading and following instructions from Mercedes Book but it wasn't helpful.
Please, if you got some information in how to get this cable in place I will appreciate if you can forward it to me.

Thanks.
Nyck

__________________
Nyck - TX - USA