Jasper,

Thank you for the mention in your post. I found an article relating to HES failures on R1100's and the symptoms were remarkably similar to yours. Seems the wiring suffers from the heat the most. I believe the author insulated the wires from the sensor to the connection which increased the life of the HES unit substantially. If you saved your old plate, there are replacement sensors available for under $30 apiece. Drill out the rivets and bolt on new sensors, insulate the wires and you've got a spare.