If I understand you correctly, it works fine without the reducer you just put in, but with the reducer in, it reads off right?
The 12v replacement gauges look exactly like the 6 volt ones. I am saying it's possible he put a 12v replacement gauge in which wouldn't be noticeable because they look the same. If he replaced decals, you REALLY wouldn't be able to tell. So, you are reducing a gauge that doesn't need reducing. That would be my guess.
If you put 12 volts on that gauge and it was not properly wired (or it was a 6v gauge), you would see a small puff of smoke and nothing would work. It is not possible to get ANY indication other than DEAD if you applied 12v to a 6v gauge without reducing. It's a 12v gauge?
http://www.classicparts.com/1949-53...2-Volt/productinfo/24-700D/#.VtsJKZwrKhc
