When you call up this performance by default the sliders control the volume of the individual parts (of which there are 2) with part 2 being more percussive and part 1 containing the individual "drawbars". If you press Edit for part 1 you can see that it employs 8 elements - you can solo these to hear how they combine to make the overall sound. To change the sliders from being part volume to element volume you must first select the part whose elements you want to control (in this instance probably part 1). Either press the part 1 Part Select button or press on the part name on the screen (you will notice that the part now has an outline around it - also the indicator to the left of the sliders has changed from Part 1-8 to Element/Operator. If you move the sliders they now control the element volumes of part 1 - effectively controlling the "drawbar" levels.

Hope this helps.

Adding how to get back to the "Part 1-8" mode of the faders ...

With [PERFORMANCE CONTROL] button lit brighter than [PART CONTROL] (press [PERFORMANCE CONTROL] if not selected:

1) To get the faders into "Element/Operator" mode which is the 3rd green LED down to the left of the faders, press the Part Select [1] button ("labeled as "1/1"). This is also called the Number A [1] button as the generic name for the button. If the part you want to control is not Part 1, press Part Select [2], or [3] ... corresponding to the part you want associated with the faders.
This mode will control the level of each of the 8 elements within a part. If you want to visualize what's changing, select the part, choose to edit this part, down at the bottom press the "All" button to turn it blue, and on the left-side of the screen pick "Balance". Now move the faders to see this effects the level of each element within this single part.

2) To get the faders into "Part 1-8" mode - which is the 1st green LED to the left of the faders, press the "PART [COMMON]" button OR press the "[PERFORMANCE]" (HOME) button. One slight annoyance is that the (HOME) button will kick you out of the faders from controlling the elements of a part as it will auto select common (in turn, selecting "Part 1-8" for the faders). For a performance like "9 Bars!" this may not be optimal to have to avoid the "landmine" of pressing (HOME).
This mode ("Part 1-8") of the faders selects the volume of each Part 1-8.

That is one minor annoyance about the modal nature of the faders. I noticed before when I wanted to use the faders for _part_ volume adjusting, I had to press the "home" key first to switch from element to part 1-8 mode. You can see the result of changing the volume by looking at the home screen grey level bars for each part as you move the sliders.

Some additional notes:

It would be nice if the performance could force either a given Part Select button OR the Common (part) button on default when switching to the performance. For me, "All 9!" doesn't automatically place me in Part Select (even when selecting from Live Set) - it's in common mode. This places an extra step prior to using the performance in its intended mode.

From previewing "All 9!" I wasn't aware of the faders controlling drawbars until this post. Incidentally, Part Select [2] chooses "Organ" which brings in levels for the leakage, dirty key contacts, percussion, etc. Kind of strange that some of the background amp noise goes away when no keys are pressed - so I just don't turn up that parameter.

I thought it was annoying that there wasn't a button near the 3 green LEDS to change the fader mode - but I suppose with the given control buttons, button pushers str fairly well covered.

Thanks for both replies that I have tried and they work fine.

I must have done this by accident in the past, but just could not repeat my actions when I tried again yesterday.

Many thanks.