'72 Valiant has no power

There is no "positive or neg" they are both HOT. Red is battery "coming in" and the black feeds off to loads in the car, as well as "coming from" the alternator.

Read through that Mad article I posted, there's a lot of "good stuff" in there. The melted ammeter they pictured looks EXACTLY like some I used to see up here on pickups with snow plows.

"Stuff that can go wrong" with the ammeter and immediate area:

The molded wire ends themselves can fail down inside the insulation, get loose and "make heat"

The nuts can work loose or "been left loose" and make heat.

the ammeter itself. Construction varies over the years, but basically it's a pair of studs inserted through the brass shunt. This is not welded, and some years is not even exactly riveted. Rather, the whole thing depends on the compression of the nuts to "press" the whole thing together and make contact.

If something loosens..........well.........

Unless "you are married' to that ammeter this might be a great time to do the "Mad mod" and do away with it.

There is a thread on converting voltmeters to fit into the cluster in place of the ammeter:

http://www.forabodiesonly.com/mopar/showthread.php?t=119480

There's three pages, read through them, This covers several cluster styles