The procedure found online is to remove the gauge screen and bend the little thingy. I'm wondering how you intend to bend those tangs back down again. The sad part is you never needed to open the gauge. All you needed to do was put some electric tape over than piece of metal on the backside of the gauge can to isolate it from ground. the 12 volt supply wire serves nothing but the limiter so take it out of the panel harness connector and route it to the substitute regulator where ever you choose to mount it. It doesn't have to be on the back of the panel.
The stamped tin speedy nuts contact only one thread of a stud, so rusty studs are degraded connections. Good luck with it.
