I have a Sony 19" Trinitron Monitor, CPD-420GS.

Here recently, the focus will change on it's own. Usually, it starts
with a "click" from the flyback side of the monitor, and then the
focus will change from mild to wild.

Had the monitor open, and checked for cold solder joints. Found none,
but resoldered some previous repairs (Q901 and Q902). Didn't find any
obvious leaking caps.

Any help appreicated.....