Illumination is the orange wire. for this type inst' panel there is normally a little weld splice buried under harness tape so this wire forks to 2 separate board connectors. I wouldn't expect a problem there. Can't hurt to check that the orange wire is hot at both connectors.
I think these connectors can be attached upside down,( evenly spaced ports? ), wrong wires get on wrong posts. Check that orange wires are on the correct pins.
Bulb sockets can be the issue too. Tiny little plastic tangs hold the socket contacts against the board. The tangs of used sockets deflect or crack allowing the socket to lift.
