My wings came from an 88 via an 87 before settling in my 95.
The bottom pivot has a stiff spring to create drag. When it gets old and rusty, sometimes the drag will become too stiff, and it will come loose at the window frame, and will just swing freely. Make sure it's not doing that, and while it's out, lube that spring assembly.
The hole in the glass where the top pivot screws in is enlarged, so you can fine tune the fit and minimize leaks. Note, however, that these windows often do leak no matter what you do. I find it a small price to pay for fresh air. Others (like the old pre-Naxja forum member who sent me his vents after he put in fixed ones to get rid of the leaks) do not.