as said there is a clasp with a phillips (middle circle) maybe loose if not you can remove the clasp and and reduce it's arch a tiny bit to add pressure on the vent windows center pin.
It may require pulling the glass/vent assembly out as a unit to properly remove the screw if rusted or stuck. not that tough a job just have another to help so you do not scratch the paint etc.
if the vent frame is loose against the A-pillar the two outer circles are where additional adjustments can be found they normally have plastic body caps covering the bolt/ nut. Slight adjustments can be made there.
The closing mechinism is whats loose cant it be tightened up looks like maybe a allen screw or something but mine may be missing, my byfogels arent working well. It will actually fall off if you hit the right bump.
it has a roll pin that attaches it to a stud, i believe a spring type washer is what keeps tension on it-- might be able to get it at a hardware store, Lawrence