At my wits end, good ole fuel gauge troubles

I did indeed ground the plug going back to the gauge upfront an it started sweeping toward full. I did test the gauge on a bench with a 6v battery when I replaced the circuit boards and IVR to isolate that.

I think there’s something on with the plug or at least the wiring section from the trunk floor to the plug end. Next time I get some time off of work I’ll try some more testing. I’m tempted to just clip the slip on plug to the sending unit and use an eyelet connection to make sure I’m getting a good mechanical connection. May of just been dumb luck that I gotten a 5v signal when checking why the power probe and lose connection when I plug it on the sending unit.