[Sean]

That's similar to the Heathkit VTVM I have. Yours looks like a later model. There probably are not many capacitors in it that would need to be replaced. Maybe just an electrolytic or two and maybe a weak selenium rectifier. For resistance it most likely needs a battery, usually a C cell. For measuring voltage from a battery you want to have it set for DC+ and the 1.5V range. Connect your two leads together and adjust the Zero Adjust pot for a zero reading. Connect the leads to the battery and read the measurement from the 0-15 scale. Mine has the original probe that has a switch that selects if you are measuring DC or AC voltage. In the DC position a 1Meg resistor is switched in.