Contrary to what the others have said here, Zeniths have a very high HV block
failure rate. Even the replacements, especially the aftermarket ones.
Zeniths do get coolant leaks, but that usually dumps on the PC boards. It
usually doesn't affect the focus. They also don't have a very high rate of
coolant contamination, it happens but not alot.
If it was the mirror the haze would be pretty much gray.
The focus is behind the front cover, and if you can adjust it for good focus,
order the block, it is about to fail. Also when you do this turn the picture to
max, but then turn it way down along with the brightness and see if you get
retrace lines. Dim the lights to make sure. If there are retrace lines turn the
G2 down as low as you can and still have a good picture, then order the block
and do not let the set run unattended. If possible don't run it at all or you
might wind up with a screen burn.
I assume you know something if you are in the service menu and haven't screwed
it up, but if you don't work on these things, you might want to refer it to a
qualified pro.
JURB