1968 Dart gauge help

John Stapleton said
Well I tested the gauge with a meter this afternoon and no continuity so I pulled it out and pretty much think I found the problem. Kind of a wimpy piece of cardboard for an insulator protecting it from the housing. I think when I reinstall another gauge I will use maybe 5 or 6 layers of tape or a piece of plastic to insulate next time. Thanks for all the help 67dart273 and everyone else for the shout outs..
Do to my rudeness when originally posting I will now include a few pics of the daughters ride to school for the next year or so. 360/904 with mild comp cam(440 lift), edelbrock performer, and holley 600 Street Warrior carb. Mopar or no car...

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The cardboard certainly looks like where it (the battery) grounded.

Insulating washers and materials are often some dsort of fiberboard. That's usually pretty good as it doesn't distort with heat - as plastics can.
To be sure we're on the same page.
The studs connecting to the shunt plate sould be snug - no looseness at all. And no breaks in the plate.
Continuity between the two studs should be perfect. On most meters it should show resistance as infinity or very very small.
If so, then you're good to go.
Just keep it insulated from any ground.