Alt. guage

I rebuilding the cluster in my 73 scamp and I have 2 guages for the alternator.
I ran a test (If thats what you wanna call it) by running a wire from the + and - posts to a AA battery and on one guage the needle just barely moved and on the other the needle shot all the way to one side.
The one that the needle shot all the way also has what looks to be a very lightly burned area right above the coil, so Im guessing that this is the bad one?