[Doug Tatham]

It's not going to be easy. You're going to need to trace the wires and see if there is damaged insulation anywhere. Check the sockets and make sure they are dry. If you have any lamps that are leaking and water building up inside, you'll probably want to replace it. You must have a short or ground somewhere, from my experience it's usually the socket. I replaced a socket one time and started blowing fuses, it turn out that the metal trace wasn't trimmed properly and was shorting out.