MishaB wrote:
You are right, that is the only moving part, a screw. There was no springs below. I do not know if the screw should be tighten or free. It is possible to "move" a lens in the way simmilar to yours description, but nothing more...
I'm not really sure I understand the situation but that small knurled knob looks much like the set screw on my Pentax bellows. Try unscrewing it, all the way out if necessary, then see if the lens comes free.