Ok, I did it. I should be proud of it as I didn't think I could do it. I jammed one of my lenses. Without thinking I removed the lens from the body while it was still attached to a tube and then I removed the tube which resulted in the cocking to move to a position that doesn't let the lens be attached again. If you notice, the coupling mechanism doesn't line up with the red dot. I noticed that it can turn freely clockwise but it springs back to the same position after a turn. Is that something I can fix by myself or do I need to send the lens to a technician?