Hi there, I'm not entirely sure what you mean about blotches, are they always on the screen, no matter what is being displayed.. like a purple or green patch on the screen? If that's the case, you probably need to degauss your screen, and stop using magnets anywhere near it. look in your instructions, and using the buttons on the front you should be able to degauss it.
Or it may just be a really old, tired monitor.
Joe
November 2005