Possible electric problem?

I guess you could call it an "amp gauge" but more properly it's an "ammeter" which measures current flow in amps - either positive or negative.

If you can get to it, just tighten the nuts on the back of the gauge and see if things work. If you bypass the gauge that's ok too but you lose the benefit of having a working ammeter which does tell you if you're charging or not while the engine is running.