I am not sure I can help either but are all four brakes receiving the same voltage/amperage? Is the 'cold' one due to a loose connection somewhere especially where the wires go into the axle? You should be getting the same voltage approximately at all brakes. Lastly, and I know this is not fixing the brakes, but get an infrared temp sensor/gauge and take readings periodically. I usually get about a 10-15 degree reading differential comparing all four hubs when at a rest stop. I think that is very acceptable. As you fix the brake issue and the hub gets warm you will want more than a hand felt temp to ensure all four are performing approximately equally.
