sailormon6, I have noticed that 99% of the problems on these gauges are not the equipment, but the wires. they were made CHEAP and used steel braids inside which got corroded and nasty within a year or two. On my boat, it was 30 years of water and neglect that gave me black insulation with grey dust inside the wires instead of metal in a lot of cases where it was near the bilge or damp areas.
A fast trip to
Radio Shack to buy new connectors and wire saves a lot of hassle. Use the old wire to act like a messenger and pull it through, then trim and attach the connectors.
You might get continuity but there will be tons of resistance and the gauge will not work right wth all of that. Freshen up your wires, it is a fast couple of hours (at most) that will save a lot of stress.