Greetings!
If this is an empeg Mark 2 (sticker from empeg), there is a known bug in the knob sliding on the shaft. You can search the board for "loose knob", but you basically contact support, and they will send you a new one with a rubber ring that will fix the problem. (The shaft is round, and the knob can slip over time, especially in a warm environment.)
If this is for a riocar Mark 2a (sticker from Rio), this is a new problem to me. Contact support.
_________________________
Paul Grzelak
200GB with 48MB RAM, Illuminated Buttons and Digital Outputs