Update on what I found inside the door, and a question- I found that the front vertical track/rail that the window is running up and down on has the bottom 3" of felt missing (worn away), and some of the rest of it is pretty worn.
http://pic20.picturetrail.com/VOL1373/13685773/24611517/413432024.jpg Also, I think the bumper pad for the door/window brace was so old it was useless, so I cut a piece of the 'gas tank to floor' material I have and stuck it in there with 3M Weather strip adhesive. Also, the 'runner'
http://pic20.picturetrail.com/VOL1373/13685773/24611517/413432026.jpg, had a circular piece of felt or rubber that was still inside the window channel where the regulator runs back and forth, so what I've got is just the steel 'bobbin' left. I bought a set of new rollers quite a while ago,
http://pic20.picturetrail.com/VOL1373/13685773/24611517/413432025.jpg ,but don't want to put 'new plastic parts' in to replace the original steel if I don't need to.
So my two questions are A), do you think that lack of felt down on the bottom of the rail could have anything to do with the failing glass panes? or will an overly tight glass pane channel cause a cracked glass? B) Is there any place that I can get the replacement part that goes over the steel roller that's attached to the regulator? (so I don't have to replace a good, steel part with a cheap plastic part).