Reply to Crossfader on Mixtrack Pro playing up

The crossfader on my mixtrack pro has started jumping when pushed all the way to the left. I have tested it in VDJ and Traktor so its not a software problem. Blew inside like others have said incase its dust and such but still the problem exists. I have read there is a way to fix it by opening the controller but do not wish to void my warranty. I bought the product from a local retailer (JB Hi-Fi) and was wondering would they give me money back or replacement? (mixtrack pro is under warranty so no issues there) or would they tell me i have to go through Numark?

any help is greatly appreciated