Reply to Help w/ Traktor Kontrol S4

NEED SOME HELP REGARDING NI S4:
I have been having problems with my left tempo fader and deck B volume fader. Both seem to be shorting out where they wont stay steady in traktor. Ill be playing a song and the tempo will rapidly change or jump values like theres a short in the circuit. Ive brought it to two repair shops already and both failed in fixing the problem. My warranty is also up with NI so I need to know what my next plan of action is. I absolutely need this fixed permanently!