hi , i have a problem with my sherco 290 2003 fan, i belive it is the black box (regulatar) made by leonelli part number 2701. i cannot seem to locate one, i cannot find a contact number for rathmels, the fan works fine off a car battery, but will not work if i bypass the thermostat. it all leads back to the black box also belive it is called a diode. can anyone help , please many thanks stu