It sounds like to me your problem is at the connector. One of the pins is not making good contact with its counterpart or the wire going into the connector is broken at the junction where it connects to the pin. Try to spray an electrical contact spray along the pins to see if that corrects the problem ( it might just be some corrosion on the pin ); otherwise try to re-secure ( solder ) the wire to the pin that appears to be bad. Keep us posted as to how it turns out. Good luck.