Thanks for all the good and informative answers.
I have fixed the problem, not in the "right" way but in a way... I found another thread about an ARF Sub with the same problem, so I used his solution simply because it was the simplest way for me, because of the tools I had available.
I simply opened the caseback, removed the shitty rotor and fake movement plate, released the crown and then filed down the end of the tube enough to let the crown screw all the way in. I've also ordered a new rotor, and a new stem because I accidentaly cut the old one slightly too short.
Simple fix that can be done quickly with a minimal set of tools.