If your front glass is adjusted correctly, "vent frame correct". The front glass does not adjust front to rear once the vent frame is Posistioned. It will adjust in and out but is fixed in the vent frame at the front. All the clearance is done with the rear glass. I adjust it for about 1/8 to 3/16 clearance and parallel to the front glass. The front rail on the rear glass adjusts at the top mount and the regulator posistion determines up and forward as well. You just have to get in there and start making small changes and you will see what you need to do. It's a PITA but once you figure out one side the other is a snap.