Posted on 11 Mar 2013
Stole this from another site!!
The answer is very gently. Try using a silicon based spray (furniture polish will do). Spray the rubber from inside the caravan and gently run your finger round the seal allowing the polish to penetrate between the window and the seal itself. Now unlock the window and gently ease the window open from the bottom. It might be easier doing this from the outside by pulling the window open at the bottom. Once you have opened the windows, clean both the window and rubber seal with warm soapy water. Once the seal is dry, spray some silicon on a cloth and then wipe round the seal. This should stop the window from sticking again.
