[RussWhite]

Bill - Not totally sure I understand your question. The rubber plug is an essential part of the replacement part you are making. One must seal around the screw you will be using as a tank sensor. I bought black rubber plugs , maybe rubber stopper would be a better description. It’s OD must match hole diameter. You then drill a hole in the stopper to insert the screw. When you tighten things up at the end it expands the stopper making a water tight seal. Hope this helps. If your probes are not corroded away I guess there could be other problems with the electronics. But, since mine was so bad it was leaking water I had to deal with it. Good luck