1972 C10 Ammeter question

[wlt3355]

I was diagnosing why my fuel gauge quit working and removed the instrument cluster to check it as well, and discovered the circuit board had three lines shorted out.

Both lines going to the ammeter were shorted out as well as one line coming from a grounding spot.

I discovered on the back of the ammeter that there is not any insulating material between the back of the stud nuts and the metal panel board, which in my mind, allows for a direct short between the battery terminal, the alternator terminal, and the ground within this panel board. (see attached pictures)

Am I correct on this that there should be some type of an insulating material between the stud nuts and the board, as there is on the back side, just not the inside.

Also could this have been the problem with the fuel gauge quitting?