DDJ-SR2 RIGHT CHANNEL FX ISSUES

Hi guys,

I ve been experiencing some technical issues with my right channel fx knobs, they stopped working once about a month ago and i had sent them to the service center they returned the controller back and all seemed to work. until 3 days ago when the same thing happened...
I have tried it Virtual DJ and the result is the same... the controller is still in warranty but i am concerned if this some sort of technical issue which would need more attention.
Would you please advise me if there can be anything done regarding this?