Traktor Kontrol S4 MK1 -> laggy knob?

Hello guys.
I'm a proud owner of Traktor kontol s4 mk 1. I'm very satisfied with it, but I have one scary problem. I don't really know hot to explain it with the words except with the word laggy. The problem is with my CUE MIX knob located in front of me. When I turn the knob fast from the left to the right (or vice-versa) it takes some time to actually process it in the software. If we say, for example, position at CUE (all the way to the left) is 0%, and position at MASTER (all the way to the right) is 100%, and if i want to move that position from 0% to 100% it will move it to somewhere around 85%, and then it will slowly make it to the 100%. I had the same problem with my 2nd FX knob on the right deck but it got fixed by itself.
I tried my controller on two different computers with two different drivers and two different traktor versions, aswell as with two different windows OS versions (xp 32bit and 7 64bit). Any clues about this? Thanks

Solved. Potentiometer was a little bit dirty. I used Kontakt spray to fix it.