I have power at that red wire side of the ammeter but no power at the black wire side of the ammeter. Could this be my problem? Can I bypass the ammeter by connecting the red wire to the black wire terminal?
Yes and yes.
Check a few things while you're in there.
Disconnect the battery pos and then check for continuity through the ammeter (stud to stud). If its open, or there is a little movement, the studs must be loose from the plate (the shunt inside the ammeter). If there is continuity, then check for a break or poor connection at the wire crimps and ring terminals.
If it is internal, then yes absolutely connect both ring terminals on one stud. Just make sure the stud isn't loose.