I would be looking for a better circuit board but meanwhile... Lift the fuel gauge. On the backside of it you'll find a slither of metal captured under folded tangs. That is the ground for the limiter. It needs to be a clean and snug contact point. Toss away that clip over one of the studs and put a flat washer or stack of flat washers and nut there. They fingered out that this clip/heat shield thingy is a pizz pour connector. Later models have a nut here. The stud is capped with a bakelite cap that looks much like a household wire nut. I don't think the stud gets so hot that it needs a cover. OK... so in the case of rally inst' panel this stud could contact a defrost tube which is sort of paper material. Could get warm enough to emit odor? I guess its possible.
The limiter and all the lamps need a complete chassis ground path. Factory relied on the few screws that attach the panel to the dash to complete the ground path. So nothing works while panel is dangling from the harness connectors except amp gauge and brake lamp. A dedicated ground wire is highly recommended. At the screw that holds noise suppression cap' is a suitable place to attach a dedicated ground wire. Other end would go to a screw in the chassis somewhere. Of course those 2 little screws at top of your board are part of their ground path. They should be clean and snug to the circuit boards pads. In the case of later model boards most every attaching screw is connected to bulbs grounds. You'll notice the lower screws that attach your board are connected electrically to nothing.
Illumination is 3 or 4 bulbs behind blue tint diffusers. It has always been so dim that we can hardly see that its on out in daylight. Improved ground should help.
A failing dimmer rheostat in headlight switch can be a factor also. I bypassed a failed rheostat in otherwise good headlight switch. My illumination is full on regardless where the knob is rotated to. Other owners place LEDs in these 4 positions or all lamp positions. And since LEDs are polarized you'll need to install, test, rotate 180 degrees if needed to get correct polarity. That's when a dedicated ground wire really comes in handy.
The loose wire and connector... If its a yellow wire it might be their tape out to door jamb switch for dome lamp circuit. That's just a guess.
Forgive me for pointing out changes/improvements in later models. Hope all this helps.
