[dtw]

1. Is the glass a good fit? There is aftermarket glass that won't fit right no matter what you do

2. If yes to 1, the problem is the trim. Even the most careful removal of the trim from the old glass/seal will cause the curves in the trim to relax/distort. The upper corners in the trim are a very complex curve - in 3 dimensions. The trim must curve upward into the corner, and also back (from front to rear, longitudinally), in order to properly seat the seal.

I carefully use a big soft rubber mallet to work the trim into the proper profile when re-installing. This is done after the install - not off the car. Also - during the install - make sure that the glass/seal/trim assembly is not allowed to 'sag' down too low in the aperture.

The things that I have seen professional installers do, to try to make the upper corners look right, are shocking.