[gschnu]

Hi and thanks for your description! I tried it with my bare hands an a thin allen key... so I soon gave up!
If you still have play in the mechanism, you should try to apply that E-shaped sheet of plastic I showed in the 2nd picture in my posting. You can see if it would be an advantage if you look at the pivot's housing's gaps when moving the shifter stick sideways. If the gaps (especially the one over the side pin) open(s) under tension, there is some play that can be successfully reduced thus bringing much more extra precision. Try it!

Take care!