Your problem may be the roller on the end of the regulator that slides in the glass channel. The originals were some sort of phenolic material that eventually wears out and quits rolling. You can get replacements out of nylon, along with a shoulder rivet to replace the original.
LinkNo idea on the hole at the end of the channel. Maybe manufacturing related.
Sounds like your run channels (the felt covered thingies in the door groove) may be worn and need to be replaced. Also the division bar (rear of the vent window) might be mis-adjusted. There's a bolt at the bottom that holds it in place.