On Sun, 24 Apr 2011 22:03:16 +0100, "Stephen"
wrote:

OK, I'll get some 22uF 50V 105 degree C ones ordered in then Do they have to
be low ESR? if so I'' go for the Panasonic FM series that I used to replace
the secondary output electrolytics.

If a capacitor has gone dry, wouldn't there be a clue like bulging tops,
leaking brown crud, and a horrible smell when they get hot?

Those symptoms occur some time *after* the cap's performance degrades
to the point of compromising the PSU.

Agree with the others, the small cap on the UC3842 is the most likely
candidate. Note that it *may* be a surface mount type and not an
aluminium electrolytic.