Dumb question, but are the windows in the "up" position? I drive my Benz only on weekends and have learned to store it (covered in the garage) with the windows cracked open a smidge. I've learned that they can "stick" to the seals in the "up" position. Just a thought -- have someone work the "down" button while you "palm" the inside and outside of the suspect window, adding downforce while the button is operated.

Good luck.

Brian16V