I use my Ernie Ball VP Junior 25k as an expression pedal in my rig. I just tested it and found that the sweep of the pedal from heel to toe goes from the value of 9 to 100. That is to say, the pedal does not sweep the range between zero and nine. Does anyone have any suggestions on how to fix this so that's the pedal sweeps from 0 to 100? Should I use oil on the pot shaft?