My 1990 740 driver side window has a large gap in the rear upper part of the window (the gap seems to be greater when the car has sat outside in the cold) that leaks air and sometimes a little water. This leak causes cold air inside the vehicle that I can feel when driving and seems to have become worse over time. Sometime it is fine unless I roll down the window and then it does not seal when I roll it back up. Any ideas to try to fix this without replacing the entire molding (too expensive).