Just returned from holiday and been trying to clean my camera after it got some spots of dust etc on it. However I had noticed that I have a few spots on the focusing screen but they wont budge with compressed air can jetting. I then tried to remove with a little isopropyl and water mix (solution contained within the Jessops Deluxe cleaning kit). This may have been a bad move as I now have some smudge marks. Looking online for assistance it would appear that many 550D owners are having problems with regards this sort of issue. I'm thinking of taking the screen out as per the online guides for a closer look. Any points to watch out for in doing this? Also if the screen requires to be replaced where are these available from at how much? thanks in advance.