DDJ-SX2 Channel Issues & Sound Bleed

I've been running into issues with sound on almost every single channel on the mixer. First it was 1 and 2, but now it's almost as if it's slowly happening to 3 and 4 as well. Essentially, all of the channel faders have issues when you bring them to full, or no volume. If I bring the volume all the way up or down on the mixer, the volume will spike down depending on how much force you use. The sound spikes down sometimes even when bringing in another track on a different channel. It's almost as if it's acting automatically adjusting the gain, but I've made sure to turn all of those types of things off and even tried the mixer in other software to make sure.  Also, when tracks are playing with the volume all the way down, there is times where the channel's volume is slightly above 0db to the point where you can hear it in a mix.

I've tried using compressed air thinking it might just be dirty inside the mixer but I'm starting to think it's a hardware problem. I do mix dubstep & riddim so I'm starting to think this controller was used a lot before I bought it, and I can see chopping tracks wearing out the channels if it's not really made for it. 

Is there anything I can really do or should I get it looked by a Pioneer repair place near me?