Erm, this might sound silly, but back in the day (at least 10 years ago) when part of my job required me to fix monitors, the standard fix for an out of focus Sony Trinitron that didn't respond to the usual knob tweaks was to hit it. With a little rubber mallet (with a Sony part code on it) Quite hard...on the right hand side, up near the top.

And no, this isn't an April 1st joke