I'm working on a bally display. Only one digit out. The 100's digit. All 100k resistors check out fine. The MC1454 digit controller is fine as well. Swapped that out with
a known good one. I grounded Q3 collector and the 100 digit lit up. I didn't have an MPSA42 at hand but had an MPSA43. I swapped it in and still no 100's digit.
Anyone experience this? Maybe the MPSA43 can't be swapped in? Looks like it's a 200v transistor but the MPSA42 is 300v. I'm not sure that matters much.

When you say print headers? I'm not following that, can you explain? Do you mean header pins? Yes I reflowed them.

Ok so here's a first.. I took out my logic probe. I touched resistor 5 (100k). The missing 100 digit came back. And that's the fix. Go figure. Just touching the
100k resistor with a little electricity to it brought it back.

I'm sure.. But it is now fixed.. I'll replace all of the 100k resistors as soon as they arrive.