A friend gave me a used KDS Xtreme FLAT 17"CRT about 10 months ago. I was grateful to get it & surprised how well it looked. Anyways just yesterday I noticed like 2 or 3 very very fines grey horizontal lines across the middle of the screen. I pressed the degauss button no improvement. Then to get a better look at them I took a dusting cloth to my screen. The lines disappeared! Then today after my monitor was on a couple hours the lines were back. So heck I thought just use the dusting cloth again. It worked again, the lines are gone. What's going on here with my monitor? Thanks.