Pantera ammeters are famous for loose connections and subsequent arcing and failure. Fire is not out of the question. Looks like you dodged a bullet for 10 years. A properly installed ammeter is not a dangerous meter and would behave as you expected ..... as long as the connections remain tight. 😉
With differing justification owners select the ammeter or a voltmeter. Personally, my intent is to have neither and instead install an oil temperature gauge.
Neither...... you ask?
In my experience electrical problems in an automobile display themselves quite clearly - as long as the early symptoms of failure have been previously experienced and are recognized - and do not need a gauge to announce their presence.
EBay is littered with voltmeters designed for cigarette lighter receptacles. Toss one in the glove box for troubleshooting when needed or buy one with USB ports for convenience.