I am in the process of trying to fit the Tri Spark Classic Twin Ignition on my 75' Mark III and am having difficulty removing the auto advance unit. I do not have the service tool so they state to thread in a correct size bolt and gently tapping it until it falls off the taper. We have tried tapping around on the unit to loosen it but to no avail. Does anyone know the correct size bolt to fit in there or any other way to do this. Thanks in advance for any response as your advice is greatly appreciated. By the way it is the Lucas Rita Unit that is being removed.