With 43V applied to the rest of the scope, it fired right up and worked properly.
I used my previous lash up which was already in a cabinet, of a Variac and isolation transformer.
I attached a bridge rectifier and a 470µF cap and adjusted to 40V unloaded.
Regulation was poor and I had to crank it up under load to the nominal 43V specified.
Now on to the SMPS repair.
I basically lifted one leg of all the passives and checked them with the ubiquitous $20 LCR tester.
The same tester was used on all the transistors and the SCR as well as the Zeners and other diodes.
R911 the 150Ω 1 W carbon comp resistor was way out of tolerance along with R937 the 8K2 ½ W one as well.
I've got some parts coming to fix the few items that have gone out of tolerance.
I almost forgot R922 the 86K6 resistor is also out of range at 88K+
The IRF820 will get swapped with something with a lower RDS on.
The TL494 is also going away just because.
That's all until pieces parts arrive.