You should be able to take the plug apart. The pins can be removed. If the wire is just soldered in the pin, you can replace it. If its crimped, well, there are ways to fix it, but most are crappy ways. We did it, because there was no way to get just the plug, back in 1970's. Later we had repair kits, pins and plugs. Clean it up and then stick it back into the turn signal. Dont screw it it, just stick it in. Take a wrench and turn the plug head off.