brake lights on 1971 superbeetle aren't working

VWs are "special" in that if a fuse or bulb is out, other weird things may happen until it is fixed. The car uses the body as a ground so you must make sure all connections (both mechanical and electrical) are clean and secure. Clean the corrosion off the bulb AND socket, make sure the socket is making a good electrical connection with the taillight fixture. I'd bet this will resolve your problem.

Thanks so much for your help. I cleaned the sockets, changed all the bulbs, and replaced the fuses, but the brake lights still aren't working. All the other ones are though. Might be time to take her to a pro, I can't figure out what to do next.