Dome light quit working

[Jeepwm69]

On my 83, the dome light quit working. Cargo light still works, which tells me it's not any of the switches.

Took the bulb out, which looks good, and measured the socket with a voltmeter which showed .25-.3 volts, so obviously I have a bad socket or bad connection somewhere. No corrosion on the terminals.

I'm guessing the leads to go the cargo light switch and then from there to the dome light, is that correct?

How does one go about fishing wires through there? I have a High Sierra so no headliner, and it doesn't look like there's an easy way to access/ replace the wires going to the dome light.