About 3 weeks ago I had a similar problem with my 1998 E320. The front passenger's side window would go up about 3/4 of the way, stop, and then go down to about 1/4 up. If I helped push it up from the outside while someone else operated the window switch, it would close fully. This indicated the electrical and mechanical parts were fine, so I just lubricated the window seals with a silicon spray for a quick fix. I need to find out if there is something better to use. The child safety feature thought something was caught in the window and would stop the glass from raising once it reached a certain point of resistance.