The original rectifier reservoir cap in this amp was the wrong value: 200µF @ 350V. Most likely the capacitor was originally intended for use in a Marshall Major. Somehow, it survived 36 years drawing heavy ripple current with over 410V across it.
I replaced all the electrolytic caps in the amp and added some output tube and transformer protection features, threw in a few NOS tubes - two Mullards and one Sylvania.
