All back together. I’m just a few minutes into a very tentative power-up (one amp, only followed by the other when I knew it had come up ok), and at this point I have no buzz, crackle, distortion, explosions, fire or anything. Not counting any chickens yet, it is very, very early days yet, but maybe it was either the carbon comps or a crap joint somewhere (not necessarily mine!).
I’ll give things a far better assessment over the next few days and see if
PS I’m a bit triggered by my reassembly soldering. It is just so absurdly easy to over-heat the tired old plastic cable sheathing, so you can tell I’ve been in there now. No iron drops, knocks or anything really dumb, just some heat.