Fuel Gauge Issue

I need some help with my fuel gauge and I'm hoping someone here can point to something I've overlooked. !976 Dart that didn't have a functioning fuel gauge when I bought it. Had zero resistance, pulled the sender and the float wasn't floating. Installed new sender, still nothing so replaced the voltage regulator with the RT Engineering unit and the gauge works. Fast forward to my Sniper 2 install using Holley's in tank pump and it works, but reading less fuel than reality, I'm okay with that. All of a sudden the gauge stops working. Ultimately I warranty the pump because it's VERY loud and Holley figured the pump was bad. Install new pump, add fuel back to tank (car on jack), fuel gauge needle moves, thought I was good. Drop the car down, go for drive a few hours later, no fuel level on the gauge. I have done everything I can think of to diagnose the issue and I'm stumped. Below is a summary of what I've done thus far.

• Ground the gauge to the battery, needle moves.
• Ground the gauge to the same ground the sender is wired to, needle moves.
• Measured resistance at the Holley connector, both sides, 39.2 Ohms.
• Measured resistance at the connector on the back of the cluster, connector unplugged, 39.2 ohms.
• Plugged connector in ~1/2 way, just enough to get a probe on the circuit board stud, 0 ohms.
• Plugged connector all the way in, 0 ohms on the gauge stud, 0 ohms on the circuit board.
• I have a second circuit board (not from a 76), plugged in the VR, added a second fuel gauge, ground the circuit board to the battery, 0 ohms at the gauge, but 39.2 at the plug when plugged in.
• Wired old fuel sender directly to the gauge, gauge needle moves when I move the float by hand.
• Wired old Holley fuel sender directly to the gauge, gauge needle moves with the float.
• I have continuity from the trunk connector to the connector at the dash.
• I have continuity from the circuit board stud to the gauge stud.
• Do not have continuity from the trunk connector to the gauge stud.

What am I missing? Everything else on the cluster works, except the right blinker but that stud is broken off the circuit board. Any thoughts on what I can do/test next? Thanks in advance.