check condition of points then if have to replace can chk dwell angle after setting point gap since Mercedes factory manuals say nothing with pointgap ill try business card then take fr there then use rpms to adjust carb after timing set using a mac et805 dwell tach and volt meter 2 leads also heard theres a little box below coil in back of resisters with a post for bosch meters some say takes best readings w/ dwell tach I don't know haven't tried yet very tricky with engineering changes thanks for yr help any more info ill post