recommend for repair of DDJ-S1

I am having an issue with the fader on the left deck of my controller. When I raise or lower the volume I get either a loud jump in volume or drop of sound. I also noticed that I am not getting as much pump in sound and have been red-lining more often to get more volume. (yes I have made ajustments with headroom settings.)  I would like to have it looked at and repaired. Any recommendations??