I am having a problem with the filter cutoff whereas when I stop moving the dedicated frequency cutoff knob the cutoff continues to creep digitally at a slow rate. It seems that this knob is still sending signals that the frequency is changing very gradually even when I am nit touching it. If I wiggle the knives for a bit, sometimes it will stop but it seems like it is getting worse. Is there a calibration function for this knob it is this a hardware issue? If hardware issue, what are options to get this fixed?