When Joe Black and I had the door panel off my Proton (to try out the permanent window fix prototype), it was pretty obvious that the bracket that holds the window to the vertical glide lost contact as the window pushed upward - the temporary fix is to "tighten" the bracket by placing a stack of washers under the bolts that attach the glide to the door, pushing it out. The additional tension prevents the bracket from losing contact so the widow goes upward as designed.

Joe's permanent fix is a replacement bracket that has extended/reinforced "fingers" on either side of the glide, so it doesn't have the opportunity to flex out as the window travels upward. The design flaw is in the curvature of the vertical glide - it bows out in the middle due to the shape of the door - instead of designing new brackets, Isuzu reused off-the-shelf components, so with time they wear out. The new bracket should fix the issue with most having window problems. It won't fix windows that have progressed further (once the rubber has split or the side-glides are mangled, or the regulator is shot, additional work will need to be done).

-- John