Since I bought my 2200 TC the brake dash light has never worked, either when the handbrakes applied, or as I recently found out, when the reservoir fluid drops. I've tried a known good bulb in the holder to no avail and cleaned the float tube of all the crispy crud along with the contacts on top. There is a supply across the wires with the ignition on but I'm wondering if there is a problem with the printed circuitry or bulb holder. Could I test for this by testing between bulb holder and earth ??