it might be off the track
which would explain the crack noise
best bet is to remove the door panel and see what is going on indside
toyota dealer sometimes will lookafter a lexus
i used to think a reg from a camry would work but i am not sure after looking at a camry which has a smaller rear window and a pillar over the window for support
also the es windows are slanted in the back while the cams are smaller with a solid small window behind
as well the es seems to have a slight pivot to the frameless window system for opening and closing the doors