You need to spray some contact cleaner on the pots inside, and spray "liberally" ( a lot) to flush out the dirt. Let it sit for a couple of hours then play.
In the meantime, use Rig Manager.
If it is a new KPA i strongly advidse against it. Contact cleaner can easly get between the display and display led backlight foil . It will create darker area becaouse the fluid it will have nowhere to evaporate.
I used this method with my KPA but only with 2-3 sprays on the encoder.
But my KPA is no longer under warranty.