few things... or couple, permitting I know how to count.
make sure your contrast isn't jacked way up.
make sure your brightness/screen adjustment aren't jacked way up.
check your focus pot on the flyback again.
if you have any excessive smearing of the color drivers, then there's a chance those are too high if the contrast adjustment won't help.
if none of these help, then it's probably your flyback going bad. I hear they're not that difficult to change out, for the $20 or so it costs for a K7500 fly you might as well dig out the soldering iron and get some practice in.
at least I'm assuming your monitor is a WG K7500... that's what our Carnevil has. considering the age and the overall shit build quality on these monitors from that period, it's probably very likely the flyback is going bad.