[Mike K]

You can measure the sender unit OHM range with a multimeter , but you need a sender unit in good working order . The sender unit should clean up Ok with some suitable solvent , I drill a tiny hole in the lid and spray electrical contact cleaner inside , the wiper arm can become dirty.

The gauge is the balanced coil type from memory. There are two bobbins inside the gauge that are wound with very fine fragile wire .