It's most likely something with the actual cross fader itself. Easiest solution is to just use the volume faders (this is actually how I dj most the time - with the cross fader disabled) You could try taking the controller apart in the potential that you could fix it without buying anything, but I doubt it. It's also not worth buying parts for something that cost 50 bucks So I'd say unless your scratching, with that controller your best bet is to leave the cross fader in the middle and use the volume faders