Hi Steve,
What type of gauge is this? Is it a Smith's mechanical gauge or a Kirkham electrical gauge or something else? If it is a Smith's mechanical, it will have coiled wire sheathing - see link to Nisonger who could repair this gauge if it is broken:
Nisonger Instruments :: the exclusive Smiths U.S. Warranty & Service Center since 1949
If it is an electric Kirkham gauge, I would start with Kirkham.