Fran,
Its OK, I have actually just figured it out..
This is what you do:
Play the song, then select GM PART. In the middle of the screen you see PART 01, just scroll to when it says PART 11. Then change the SOUND set to DRUMSET for channel 11 and now it will allow you to select a drum kit and Volare !!! It starts playing drums..
Interestingly enough, I have just used this method to actually store GROOVES permenantly in midi tracks... now the midi files can sound a little more interesting than normal.
DannyUK