Lost my Fuel and Temp Guages at the dash in my 67 Dart

Back story: A few months back I had power locks and a viper alarm system installed on my 67 Dart. It's a California car in very good shape and is a daily driver.

Upon leaving the alarm install shop I got about half way home and noticed my fuel and temp gauges weren't working anymore. Turned around and went back to the install shop to fix what ever they broke. So they proceed to hem and haw but finally agreed to look at it; first thing they did was remove the fuse box and put it back in and that worked. So I left only to find the problem reoccurring again and again over the next few weeks. The gauges would work and stop, sometimes come back on by themselves, sometime not. Everything else works fine.

Fast Forward:
What I've done is wiggle the fuse box with slight upward pressure and have gotten the gauges to come back on a few times. This has worked over the last several weeks. That doesn't seem to work anymore.

I have gone thru the wiring cluster around the fuse box a few times and cant find a loose or pinched wire anywhere. The fuse box will not come down far enough to really see what is going on in there on the wire side, so I'm blind there. It looks like the fuses are all good but I'm going to replace the one fuse that links to these wires anyway, but that is a long shot as the problem is intermittent and if it was a fuse problem, it wouldn't just come back on like that.

The way I understand the wiring diagram, the fuel and temp guages go into the same fuse, so maybe I have a bad connection there in the fuse box its self? I'd like to visually see that but I cant get the fuse box in that position because the wiring connectors and such are all up against it. Is there a trick to getting the fuse box in a position so you can see the wiring side?

The wiring is solid in this car so rewiring or going crazy like that doesnt make sense, so I'm not going there.

This is a loose wire or connection issue and I want to confirm I'm on the right track.

Any thoughts or prayers (lol) would be helpful.