Ammeter Gauage for 74 Duster

Safest thing to do is disconnect the Amp gauge completely.
They have been known to start fires.
The description of your gauge is typical.
They aren't all the same. Some amp gauges are better made than others and well away from water damage too. Even though... There can be a totally different design flaw and good reason to bypass the amp gauge or convert the amp gauge to a volts gauge. Such is the case with a-body rallye panel (That conversion is more complicated in some models than others also). No need to get into all of that here. Some owners are willing to live with a in op gauge in their instrument panel while others are not. Good luck to all