Common dash cluster issues question

Hi all,

I'm having the very common problem of my gas gauge not reading anything at all in my 71 Scamp. The temp gauge has slight movement to it with key on, but I don't think it's reading as accurately as it should. This was all working before I took my cluster out to have the speedo repaired, and following a 2-year hiatus because my steering box needed a rebuild (props to Straight Line Steering in San Jose), I'm finally trying to get everything working again.

I found that one of the bulb sockets has a broken tab, so I just swung by both NAPA and O'Reilly in town and neither had the socket in stock. While I'm waiting, I'm hoping someone can provide some tips on what the issue might be. I replaced the cluster voltage regular with a solid state model a few years back, so I hope it's not that. How does the cluster get ground? Could I have an issue with the screws connecting the cluster to the dash itself? Having just put the steering column back together, I'd rather not take it all apart again to remove the cluster. Can one bad socket cause this behavior?

Thanks for any guidance - frustrated that I don't have a replacement socket today. O'Reilly will have one tomorrow, NAPA not until Tue/Wed.

-John