Leaky capacitors need replacement?

If you are ordering caps, you might as well order and replace all the electrolytic while you are at it. Also there is never a problem with getting higher voltage or higher temperature caps, in fact it is recommended. Just check the size. You’ll be quite surprised with how much better it’ll sound when you are finished;.

On the electrolytic on the boards, I would recommend Panasonic FM, Nichicon KZ or FG or Elna Silmic II.  These caps all perform at a very high level. 

My gosh, I’m rebuilding 2 amps right now that are 35 and 38 years old, every cap in both amps were in better shape than those. I didn't catch in the thread which amp that you have. I don't think that you'll find most of those caps in what I recommended in the voltages that you'll need. But I would definitely change any caps with the best that I could find and make sure that you get high enough voltage ratings.  Good Luck,  Tim

I'm not as in depth about amp building and repairs as others around here, but now that I see this,  I don't see why you couldn't do what you wanted to in the first place and use a decent metalized polypropylene there, say 33uf/400v.  I don't see any reason why a bipolar wouldn't work there.  Since Ralph chimed in here @atmasphere    I would get his expert advice