I know this has been hashed over and over, I have read numerous threads. But even with the diagnostic steps, I can't seem to find the issue.
I have found that I do not have 12v or 50v at their respective test points.
I show half a volt at the banded side of D1. So I replaced it. Still the same. Replaced it again, still the same. Went ahead and also replaced D2 Q2 and C2 while I was at it, since I had them handy. I have verified continuity from leg 2 of Q2 to pin 5 of J114 and leg 3 to pin 2. Both are good there.

Still no 12v or 50v. The fuses are indeed good. BR1, BR2, BR3 and BR4 were all also recently replaced. I can't for the life of me figure out why I have no 12 and 50 volts. I have put the SDB into a TAF and still have the same issue.

What am I missing?

Ohhh Let me check that!! Thank you!

That looks to be the issue. I have no continuity between the positive leg of BR1 and D1.

Ok, well I jumpered that broken trace. the 50V test point now reads 74.5, still no 12.
I'm tired and done for the night. I will dig some more in the morning.

Oh yea!! I forgot about that. Thank you!
Tomorrow, when I can see again, I will run thru all the diag steps one more time, now that 50V is restored.

Went to test it this morning and now the 18v rail is down. I rechecked the Bridge rectifier, found I had a bad solder joint. These old eyes don't work as well by night Fixed that, hooked it up and Success!! 12v rail!! Then a cap blew.

Replaced the cap and so far so good! Thank you all!