For those of you who (like me) hate the abrupt "all or nothin" approach that this button triggers, there's a workaround. You need to assign an insert effect to the organ you want to use, and call up the graphic that shows the Leslie switch. You can easily toggle between Fast, and slow with this screen switch, and you can probably assign it to another controller, but not the dedicated button above the joy stick. Seems odd, but for now - it's a workaround.