I have a PC3, not a PC3K, so the owners manual pages are different; however the operations are basically the same. page 6-67 of my owners' manual shows the answer. In your setup, select edit, select the zone (assuming the KB3 is in zone 1 as that is the default), go to the MISC tab. On the bottom right shows leslie pedal. Set it to "Sustain", it might be on "SOST", which is footswitch #2 on the back of the unit. Sustain is probably set to off, because if it were set to on not only would pressing the sustain pedal change the leslie speed but would simultaneously sustain the notes. As a hammond organ doesn't use a sustain pedal the Kurzweil programmers simply used the pedal to control leslie on/off using the sustain pedal while at the same time turning off true sustain. This allows the users to only need one sustain pedal, rather than a 2nd pedal for a footswitch leslie control. If you had a 2nd sustain pedal you could instead plug it into footswitch #2 on the back of the PC3 and set the leslie pedal = SOST (turn the dial two clicks more to the right) also known as CC#66. So Kurzweil allows you to use ANY Control source that you want to change leslie speed but typically defaults leslie speed to CC#64, which is typically controlled by the sustain pedal; then simply added a parameter in KB3 mode to turn true sustain on or off. So you could actually connect a 2nd pedal to FS#2, set the leslie pedal to SOST (CC#66) and then also turn sustain = "on" and then the 2nd pedal would control your leslie speed and the regular sustain pedal would actually control KB3 sustain just like it does for other non-KB3 programs. I actually have elected the SOST approach and use a dedicated pedal for leslie control which sits on my left side while a 2nd sustain pedal for true sustain sits on my right. I've been doing it this way for years and it just works easier for me to add a 2nd pedal rather than one pedal for both functions as my right foot is on the expression pedal so a sustain pedal on left foot doesn't work for me. Different horses for different courses.