The machine is Taxi. The left backbox GI is out. C-A-B lane lights are out. 20k-40k-etc lights are out. Left sling lights are out. Jet bumper lights are out.

All fuses are good.
No connectors are burnt.
Unseating / reseating doesn't seem to change anything, so I think even though some are ugly, connectors are ok.
I've tested the lamp matrix per Marvin's guide, all rows and columns are testing ok.

I'm guessing my next step is to just start replacing all connectors in the thing. But I'm hoping that this sounds familiar to someone and they can say that there is a particular bad diode / shorted socket / underpants gnome that would cause specifically these lights to be out.

So does anyone have any insight before I start replacing connectors - the slowest (and I'm thinking least likely to be productive) solution?

Thanks guys, it sounds like relays are the next step. I'll check them tonight or tomorrow, as soon as I get a chance!

Ok, I'll try that too, thanks!

It is sorted out now... picking away for a long time. I think the solution was a combination of everything. The connectors to the relay board under the playfield were loose. The pins in the 4 hole GI connector were questionable. I did end up replacing the GI connector at the board as well. It didn't seem that any one thing was contributing, but after doing all these things together, I have fully working lighting. Thanks for the guidance!