What I would recommend doing is removing the big PC board and reheating all of the joints on it. I would also loosen the hardware on each TIP50 and check to be sure that the black shoulder washer is situated so that the shoulder fits into the hole on the TIP50C. When we see the B+ voltage drop to below 100V when someone has installed a Speedball, this is usually from an installation issue with these parts.
When you have the big board out, you can just tack in the 3K resistors on top of the upper terminals to be sure that the basic build is still working well. I would also post some photos of the bottom of your big PC board and the wire jumpers sticking up on your amp.
The one area of concern on your large PC board is that the TIP50 transistors aren't well soldered, especially the middle legs.
