Yeah, what KENTON says, is a voltage 'reducer', down to 5 volts from 12. You NEED to pull it, and test it, to be dang sure it is working. If it's not, you can burn up your gauges!
Other than that, just start with the basics. Battery disconnected, the instrument panel out, so you can get to the backside of it.
Things to check is the panel circuit boards. Mine is a 64, 62 probably shaped different, but same idea. Guessing it's okay, but won't hurt to look. Should be one, or two sets of pin connectors, with wiring blocks attached. Power supply to each gauge, except amp, off those wires. Ammeter is wired direct.
Check for good ground...body to dash, dash to instrument panel base (while it attached).
You can use an ohm meter, to check wiring, and the circuit boards. Sometimes they can get shorted, and will burn out from a section of the circuit.
Power supply wires can be checked with a test light.
Take it slow, and if needed, ask more questions. Some of that stuff can easily be screwed up, not doing it right!