Your gauges will have a neutral wire somewhere. The positive line goes out to the sensor, back to the gauge, then it returns to battery negative.
I would look for a place where the negatives for the gauges is, then try running a good solid wire from battery negative to that point.
Often what happens when the neutral wire comes loose is the current can't return on the regular negative wire, and instead finds it's way through another panel gauge and goes back through a different path to battery negative.
Mike
2012 Winnebago Impulse Silver 26QP
2005 16.6 Double Eagle
2018 Jeep Wrangler JK
previously Snowbird Campers,
Triple E Motorhome and Fifth Wheel