Hello Jim I had the same problem and purchased a window scraper from Dulux Decorator Centre. The scraper itself is pretty much like a normal scraper except with a very sharp blade ( so be careful if you do decide to purchase one. I think they are also available from B&Q and wickes etc. My method of cleaning was to get a sponge with washing up liqiud and water and dab over the affected area, then used the scraper over the whole window. I then finally used Mr.Muscle window cleaner to polish off. The result of this method didn't leave any scratches atall. I hope this helps :-)