How can I test my ammeter gauge to see if it's bad?

[WH23G3G]

On this 65 Valiant that I've got running good now the ammeter gauge needle doesn't seem to move. It's in the middle but when you turn on the radio, or the headlights, or the heater the needle doesn't even move. However, the charging system is working good. I have the original gauge that was in the car and a spare and I remember I applied power from a small flashlight battery when I had the gauges on the bench and I got some movement out of the needle. So I figured they were good. In the 65 Plymouth shop manual it shows some kinda fancy dial meter specific for Chrysler mechanics that I don't have. Is there a way I can test the meter in the car to know if the gauge itself is bad or what else could it be? It has an ammeter, temp gauge, and a fuel gauge. The temp gauge is the only one that works.

[b5blue]

Leave the lights on for 10 minutes with the engine off. Start the engine and the gauge should show a recharging indication to the right as it increases amps output to recharge the battery.

[WH23G3G]

Yeah I can try that. But we had it running for like 30 minutes idling and to see if the gauge fluctuates or even moves at all. I turned on the headlights, radio, and heater but I couldn't tell if the needle moved or not. I know a lot of people have said those nuts on the back come loose or maybe I don't have the washers in the right order. So I could check those to make sure they're tight. Is it supposse to have one of those white strips connected between the two studs? I think my 73 Charger has one, and I can tell it's working right.

[b5blue]

  I've upgraded my 70 Charger to a 120 amp Denso Alt. and as the car has solid state voltage regulator from the factory it may not "act the same". My system reads to the positive after starting showing quite a bit of amperage to quickly pull the battery up to full.
  After the battery is full the needle is just about dead center when running. (It's not been calibrated in 42 years so possibly it should read dead center, at worst it reads to + the thickness of the center mark.)
  Upon turning on anything while running it reads a "reaction bip", bumping to the positive slightly then returning to center quickly as the regulator compensates for increased load by increasing Alt. output.
  I'd think your gauge should read similarly. It should show or read to the - side of the gauge if the engine is off, the key is in "run" and your headlights are on also. 

[W4ATL]

If you turn on the headlights the needle should move to D. If it doesn't the meter is probably bad.

[Chryco Psycho]

Or someone has installed a bypass either connecting both wires to one post on the rear of the gauge or installing a wire from the alt directly to the battery terminal on the start relay .

[WH23G3G]

I checked today and made sure the nuts on the back are tight and they are. I also turned on the headlights for about 10 minutes and didn't see the needle change at all. Then I started it up and ran it for a few minutes and turned on the headlights, wipers, radio, and heater and I didn't see the needle even flicker. I'm guessing the gauge is no good. When it's off the needle isn't straight in the middle like the spare gauge I have. Since I'm going to change it out, I'll just swap the whole gauge cluster out. What are you suppose to clean the circuit board with?