Dash lights not working on 73 Duster

In that case a voltage drop may not be present. Lets get close to 12 volts going on the orange wire. We're looking to have dash lamps, plus glove box lamp, shift indicator lamp, radio dial lamp... What am I forgetting? There are only 3 or 4 illumination bulbs in a inst' housing and they are behind blue tint diffusors. Then there are the 2 to 4 additional bulbs on that same circuit...
At 9 to 10 volts, questionable rheostat? , crusty fuse clips?, I can imagine the inst' lamps did come on, so dim you couldn't see it. When the 2 to 4 scattered illumination bulbs burn brightly yet inst' panel lamps remain dim, then we go back and look at the ground path of those lamp sockets.