If you have the orig. Westinghouse, the wire should not be connected to the studs or housing. The 2 studs is bolted to the housing (or rather riveted to the panel) so there is always a short connection between them.
The hot wire from the battery should go uncut in the loop under the meter, 1 or 2 turns and then to the switch. The meter is not connected to wires in any other way. 1 or 2 turns in the loop depends on what the needle indicates regarding ampere, meters can have different sensibility and that has to be checked. The meter indicates same amperage regardless of what kind of isolation the hot wire has, thin or thick plastic or old fashion cloth isolation.
The bracket should have insulator washers in the holes to isolate the studs from the bracket, I don't know why, but guess that has to do with the magnet inside the meter...It can depend on the version of meter/different way it is assembled internally. In any case wires should not be connected to the studs.
Water condensation and rust is a problem inside the meter, so a cleaning and restoration is not a bad idea.
There is not many parts in it but the needle and the thin magnet inside are delicate and difficult to replace. Be aware if a stud is loose, it holds the thin magnet and should not be turned and the stopnut must not be torqued overly hard or the magnet can split in pieces.
