DDJ SB3 Headphone Cue issue: Pre cueing bleeds into Master Audio

So I've had my DDJ Sb3 and it will do this thing where is will sometimes work and then sometimes not work (and go off and on in the same set). It's really embarrassing live. The Master Audio will be lit up and when I go to cue with the headphones and press the #2 (for example) button, the audio will just play into the master audio. It will not quiet down at all. I've tried rebooting the computer. I've installed the newest drivers. I even called Pioneer but they just emailed me some Troubleshooting guide which didn't address the problem at all. I'm running Serato Pro. Why is this working sometimes and then not? I'm using Pioneer DJ Speakers at home with an RCA cable and then RCA cables with an XLR adaptor at my club. It would be one thing if it never works but it's super annoying that it works sometimes and then doesn't because I think it's fixed and then it messes up. I have a big show on the 23rd and I need to know if I need to return this and get a new one or what. Help!