I have a 460 Ford running a 2 wire Motorola 37 A model # MR12N451D that is only running on about 10 volts on the gauge. I pulled it off and took it to have it test at 2 places and neither (pep boys or O'Reilly) place could do it. Is there a easy switch from this 2 wire system to a 1 wire or should I purchase a new one or have this one rebuilt. Any help would be greatly appreciated!