To replace that clip isn't really necessary but it never was a great connector from stud to the board. The limiter is the heat generator. Once it is disabled the clip could be replaced. If you want to attach the 5 volt wire from outboard regulator here you will need to replace the clip with different hardware. At the risk of causing more confusion... the 5 volts is supplied to 2 gauges via the printed circuit board. You can attach the 5 volt wire to the temp gauge post that is on the same copper trace ( as shown on web page you referenced ). Ring terminals under pal nuts has proven to be a "iffy" method. How I do it and recommend, go to Home Depot or any hardware store and buy a small package of 10-32 hex nuts and a package of #10 internal tooth washers ( again just like whats on your amp gauge). With original pal nuts in place, the stud is plenty long enough to place a ring terminal, a washer, and nut on top of the pal nut.
Now allow me to ask a couple questions... I think yours is the braded screen design. if you did open your gauge, How did you open? How will you close?