It seems nothing is broken, however, when I move the joystick to the right, it does not come back anymore to its center positions. Moving to the left, up or down makes it go back to the center position.
The red circle shows on the right one of the joystick spring ends; this end goes through the small gap left of it. The reason that is possible is because the two white elements (which rotate around each other) slightly move away from each other, which is visible in the blue circle.
However, I don't know how to keep those white elements together ... maybe I lost an item when I tried to fix it earlier... I hope someone has a picture or knows how it should be kept together.

Kind regards,
Michel