I do sympathise old boy. In years past, I never gave up on anything
either,
but I must admit that these days, sometimes I do, out of both a need to be
commercial and keep the wife off my back for not earning any money, and
out of sheer frustration. I think that latter condition is something that
creeps
up on you with age. Suddenly, some things are more important than not
letting some inanimate object beat you ...

That said, I reckon that this baby has got to be worth one more go if -
and
*only* if - you can lay hands on a Variac, so you can wind up the input
power to make the rails just high enough to take sensible measurements,
but low enough to stop the ouput trannies releasing their magic smoke ...

As William says, give it a break over the weekend, then come back to it
with fresh eyes (and a Variac !!) on Monday. If you do, carry on keeping
us updated. It's an interesting saga, if a little frustrating for you.

One of the reasons I've enjoyed helping is that you've explained exactly
what you've done, which makes the process fun -- and educational, too!

PS: I have several working Advents. Let me know if you want me to check the
voltages on a "good" one. I'm willing to do it "live", in real time, if we
can find a time suitable for both of us.