65 were nad for the sockets not grounding in the housing also.That and the brass terminals in the socket that touch the bulb contacts get deep in the hole and the springs get weak.There is a flasher as said and if one side flashes its good.Get a test light and see if the one has power to it.The columns on these are simple.Only has i believe 6 wires.Does the TS stem move any?They will come losse.I know had mine for 40 years.Rocky