Well, my original one does it, but the one i got from kev doesn't seem to...
But basicallly turn up the treble and bass to full, level on full, gain on full (you get teh picture)
With the Mode switch, wedge it between the OD and DIST settings. Gives out a wailing tone. Manipulating the bass and treble controls changins teh pitch, and the attack switch shifts it between three different base tones.
Have fun