"bryanska" wrote in
ups.com:

Can you tell if a capacitor has leaked by dissecting it?

My JVC stereo is humming loudly. There are signs of an obvious
capacitor leak around three large capacitors on the board. Brown crust.

I replaced two large 6800uf 40v caps, but the humming remains. So I
pulled the third cap, a smaller 3300uf 35v unit.

For fun, I dissected all three.

It's not a good idea to dissect electrolytic capactiors. They have nasty
chemicals inside them.