Korg Pa1000 Quick Manual page 49

Playing and controlling the Sounds |43
Using the joystick
Moving the joystick left of right usually changes the Sound's pitch. Moving
it forward usually trigger modulation, but this depends on the selected
Sounds. With the electro-mechanical organs, pushing the joystick forward
changes the rotary speaker's speed. What it does when pulled back depends
on the selected Sounds. Just experiment!