cap gone bad?

Pretty sure this bulge is not usual, but wanted to confirm.

Ceramic gumdrops, especially older ones, weren't always the prettiest components. I imagine it didna look much better when it was shiny new. You'll usually see either cracking or burning when one overloads, and they don't tend to drift much over time.

It's bulging in electrolytics that you have to worry about.

Easy enough to test if you have a VOM that does capacitance, but you'd need to remove it from the circuit to get an accurate read. Most good VOMs will also have special short leads to minimize read errors.

PS ... is that normal on that amp, or a bypass mod?

"orange drop" caps are dipped in a plastic liquid coating and it doesn't always dry evenly, it's likely a good cap unless you hear or measure something wrong.

Thanks guys, I guess I will test it to see.

This is actually on the Dynaco amp i bought a few months back.

That's an older version of a Sprague "orange drop", one of the better quality capacitors around. Poly film, it is almost certainly OK. You can use a modern capacitance tester to check for value, but they will not test for leakage at meaningful voltage ratings. I wouldn't worry about that one, however.