So, long Story short:
The Problem is, that the upper circuit Board is mountet very close to the lower one, so when you put force on it, they touch, create a chort-circuit and make the controller go crazy.
http://www.nhx-music.de/stuff/emx-1/1.jpg
To Fix this, you first need to take of the blue or red frontplate by pulling of the plastic knobs and loosening the hexagonal bolts.
Secound, unscrew the 4 grey screws on the plate below (see Image).
You don't need to unscrew the black screws.
[
http://www.nhx-music.de/stuff/emx-1/2.jpg (•BILDLINK) ]
You now can take of the top part of the unit.
My solution to fixing the problem, was to put something in between the circuit boards, to prevent them from touching.
Considering that the EMX uses tubes, and tubes tend to get hot, i wouldn't use any flammable material like normal paper. I used baking paper, but a better solution would be thin plastic foil or something similar.
So i just had to cut out a piece in the size of the circuit board, tape it onto it. And i was done!
[
http://www.nhx-music.de/stuff/emx-1/3.jpg (•BILDLINK) ]
[
www.nhx-music.de/stuff/emx-1/4.jpg (•BILDLINK) ]
I tested it the whole day, i didn't experience a single knob jitter!