1970 Dodge Dart Passenger Side turn signal

Still seems like grounding, to me, and might be "right in" the sockets. Do some searching, and try to find a drill driven wire brush that either will fit, or can be cut down to fit into the sockets. you might be able to take a coin, (power off!!) and fit down into the socket to protect the terminals, or you might have to "unwire" the socket, but get a wire brush down in them and buff them clean