Hi Giovanni

The standard cc code of the modulation wheel is 1, and pretty much every controller has this set as standard.

Virtually all VSTi, hardware synths etc. use the modulation wheel on organ sounds to change the rotor speed between fast and slow, (Forward fast, back slow) so it would be unusual if Roland changed this.

Check the Midi settings on your controller to make sure it is sending out modulation wheel information, and that the Roland is set to receive modulation wheel cc code information, hopefully this will then allow you full control of rotor speed.

Hope this helps

Bill