I was able to replace 3 out of the 4 caps with electrolytics. The fourth one, I busted a trace off the motherboard so I couldn't install another. I suppose if I really wanted to, I could follow the trace, but I won't bother. All these caps failed open, so I don't think it minds too much that I can't install another. The audio oscillations seem to have gone away after I replaced the two closest to the sound chip.