RedFish said

The red wire at end pin feeds the high beam indicator bulb. The black wire did feed 12 volts to the inst' voltage regulator. The 2 do share a chassis ground at that screw. The little narrow spot in the copper trace serves as a fusible link. We have seen that burned open on other boards. Some fault caused it. A failed regulator? A sender wire touching ground somewhere? Who knows?
If this was mine.. I wouldn't bother to patch the board or the loose pin. A solid state regulator package with 3 wire leads could be mounted elsewhere. Attach the black wire to the aftermarket replacement regulators 12 volt wire ( typically red ) with male and female spade terminals.
Use a ring terminal with toothed washer and 10-32 hex nut ( like on the amp gauge ) to attach the regulators 5 volt wire ( typically yellow ) on top of the OEM speedy nut at either temp gauge or fuel gauge. The copper trace that goes to both of these gauges conducts the 5 volts to both. Look at your pic. If you know the center is 12 volts and the right is ground, the left is 5 volts. Follow that trace to both temp and fuel gauge. And of course the regulators ground wire ( typically black ) goes to ground. You could use 3 ring terminals and force #6 sheet metal screws down into those original slots but... why risk cracking the board if you can make better connections elsewhere. Some inst' panels don't even have printed circuit boards. Instead every wire is attached where it goes. A bit of both works too.

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