65 Valiant dash lights, oil light, and trans indicator light not working

[WH23G3G]

I'm try this board too because I tend to get good feedback here. On this 65 Valiant I'm in the process of getting back running. I've got all exterior lighting, cigar lighter, wipers, door switches, dome light working. The only things that aren't working are the radio light, dash indicator lights, and the oil light bulb. All the bulbs were replaced when I had the cluster out. It's got a socket that plugs into the back of the printed circuit board like on my 73 Charger. I had to replace the original harness because it had been hacked so many times and had a melted alternator wire. The harness I have is from another 65 Valiant that's in good shape. There are no breaks in the wires, no splices. I know the dash lights, trans indicator light, and radio light all share the same fuse. But I'm not sure about the oil light bulb on the dash. It's got a brand new engine/forward light harness so the oil switch is plugged in. Battery is a 24 series fully charged. The only problem I see is some minor surface rust on the fuse for the instrument panel and a couple other of the fuses but those other systems work. The fuses are not blown but who knows how old they are. It's probably a bad ground like it was originally on my Charger. I had the same problem with it when I put the dash harness back in. I can't remember what fixed it. What's the common ground all the illumination lights share? What can I check with a test light?

[RogerDodger]

Headlight switch?