Hey,

  Two things that may be happening with your window vent:

  1.) The pivot hole at the bottom is rusted out (like mine) and is so loose it can't be adjusted up. If this is the case you will have to replace the vent window frame. You can tell by pulling up the rubber seal and looking at the pivot with the wing window open.  What I've found is the vent drain gets plugged with goo and the only exit for moisture is through the pivot hole which rusts out.

  2.) the clamp at the bottom of the wing pivot needs snugged up to the bottom of the vent sill.  Open the door all the way, remove the panel and take a look up in that area.  You should see what I'm talking about.  The clamp slips up the pivot shaft, so repostioning it may fix your issue.

  Brian