Hi Wizard,

I suspected those were the ones - they're marked c402 and cr402 on my
board so I wasn't 100% sure. That diode checked good but I tried a
different diode with similar characteristics in it to see if it made a
difference at all, but it didn't. I don't have any box caps like that -
I'll have to order some and replace all those suckers. I was surprised
they weren't electrolytics...
Much thanks for your help!

Kevin