No dash lights

Well, if you look at the traces on the board(s) the screws that attach them are ground points. There should be a clean contact spot under every washer at every screw. If those are good the entire housing becomes a ground path for all. Just one added ground wire anywhere would ground the entire housing. Like the pic above of a later model panel in test bed, the one ground wire should ground all ( except the brake lamp bulb, that one bulb is routed to 2 pins/wires ).