Drivers window problems

[Fireslayer]

We recently had the drivers window replaced, and about a month later when the window is rolled down to about 2/3 there is a bang where it catches on something.
My guesses has been the inside of the door (the part that comes off when gaining access to the window)
I have pulled it apart 3 times and I can't figure out what is catching. It will work fine for a week or so then it starts again.

Has anyone else had this problem? Any guesses?

Thx
Dave