My window used to come up at an angle, turned out to be a broken regulator bracket. One corner where it is pop riveted had broke away from the rest of the bracket. The regulator bracket is thin and I would assume it flex's a lot until it breaks one day. With this in mind I couldn't see the point in buying another thin one which will do the same. I took mine out and welded it back together, works fine now.
Regards Clive