Ammeters are simple and often can be fixed. The big problem with the actual ammeter is that the studs are not brazed/ soldered to the shunt. The studs pass through a stack of insulating washers and the dash housing, which is plastic for some models. So if the nuts get loose or the plastic softens, the studs get loose and lose good contact with the shunt. After that you have a "rolling snowball" except it's a "fireball."
