DJM 900nexus issue. One side is louder than the other

I've notice lately one side of my speakers is not playing at the same level when using my DJM900 nexus mixer. For example on channel one(A) the base is normal but when I cross-fade over to channel 2(B) there is no base at all coming from one of the speakers. It's seems after a while, say a few hours into a gig, one side is louder than the other. Even the led sound levels on the mixer appear uneven. Does this mean my DJM 900 nexus is going bad or needs service? I've only had it brand new for a year and a half. I've used the DJM with CDJ's with Rekordbox and Traktor.