The CH and the RCXL clone of CH work as good. They both somehow can ignore the first magnet and fire on the second. If I remember correctly the first magnet is installed with opposite pole to the second. Terry can set you up with a sensor that rotates to get the 28* advance needed for either to work. And/or slotting the sensor holder will allow using the origional screws. A spacer is needed or use shorter screws or the screws will be too long and penetrate too far into the bub.