Hi!

While your monitor's problem could be due to an actual failure of something
inside, it is very possible for a monitor's focus to drift over time. I
recently fixed an HP Pavilion 17" monitor to "better than new" focus as per
its owner by carefully adjusting the focus control on the flyback
transformer. I've also done this to quite a few other monitors and for the
ones that it has worked for, none have needed any other repair.

However, before you do anything, be sure you are confident in your abilities
and that you can be safe while you are doing this. Monitors contain high
voltages that can cause painful injury or even death. This is true even when
they are unplugged and left sitting around. They also contain AC-line
connected parts which are very likely to cause death more than injury if
accidently contacted. There is also the hazard of tube implosion if you
scratch or impact the picture tube. Stay away from the wire coming out of
the flyback, use ONLY a nonconductive tool for making any adjustments and do
not wear jewelry, a watch or other conductive items that could dangle inside
the monitor and give you a nasty surprise. Most importantly of all, if you
do not feel comfortable working inside your monitor for any reason, don't do
so. Refer it to a qualified shop or get another. It is not worth your life
or well being for a monitor or any other device.

So...if you have nothing to lose by trying, remove the cover from your
monitor, locate the flyback (large, usually black, with a wire coming out
and going to a sort of 'suction cup' on the CRT) and look for a FOCUS
control. There may be two of them. Display something on the monitor and use
a nonconductive tool to make adjustments. Watch the screen as you do. When
you have the focus fixed, remove your tool, turn the monitor off, be sure
it's unplugged and put it back together.

William