Little Red was converted to 12V when she had her 1600 put in but there wasn't anything done (as far as I know) with the wiring and my fuel gauge is still the original 6V one but now it doesn't work. It stays at 3/4 full even when the key is removed and it gets quite warm. I think the light still works in it. So - do I need to get a new gauge? Do I need a new sender unit? Do I just need to put a new part on the original gauge?