Hi If your window in the back doesn't go up but surely goes down,then you probably have green piece broken. I did this about a year ago and it happend to me again on my second B6 audi, and i know its very commong because i had lots of people email me asking how to fix. So here is SIMPLE SEARCH thread, please add to DIY section:

Im not responsible for any damage to your car, you are doing it on your own risk!!!

Door panel removal is easy and can be found anywhere.

when you take off door panel you'll see this:


take off center plastic panel and motor, not hard but screws are soft so be careful




I circled red the screws that hold window frame inplace, if it doesnt start moving freely i may forgat one. i did it like a year ago i think. DO NOT REMOVE DOOR LOCK SCREWS unless you are 100% that lock is stoping frame from being removed. Once you pull it out CAREFULLY it should look like this


remember that blue pentagon looking thingy position and where cable tubes are and what color, its VERY IMPORTANT they are different colors and length, dont worry it has tight tension on it, but once you take it off you'll have alot of cable freed. when you replace it make sure there is no empty track present on that wheel.
here is what broke on mine and how i fixed it




i got nail made a grove in it for cable and placed it like this securing with zipties



after that i filled it with EPOXY FOR PLASTIC on both sides and it worsk like a champ.
Hope that helps, good luck on your project!!