I just ordered one of these Protizmo units and connector. The total was $42.00. I'll let you know how it works out but I think it is promising. They state that it is compatible with common ground and the original rheostat. You connect the original rheostat wires to the unit, connect 2 more wires from the unit to the rheostat, and add a ground. It is tunable to work with rheostats/potentiometers in the range of 4 Ohm to 10k Ohm.
Steve
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