Well spotted that man !!! Hit the nail well and truly on the head !!! Nice one WR . Can you tell I'm in a good mood ? I hunted out the resistance values for that particular unit and how to test for duff coils , Also tested the HT resistance and they were as they should be . The primary coils were spot on but the secondary coils were reading as an open circuit with no reading at all . I think as Tomearp suggested , sitting with the engine running , the excessive heat has finished them off . Will order Up a new unit tomorrow.