Does copper wire go bad?

Update: I did some more testing. Simply by raising my idle speed from 600 RPM to 750 RPM it brought the voltage at the battery from 12.8 to 13.5 volts. That was enough to get all the blinkers flashing correctly at idle. I didn't realize the alternator/voltage regulator were so sensitive to idle speed changes, maybe just due to everything now is 45 years old.