DJM 400 faulty phono output

 Hi guys

I've just bought a DJM 400 mixer on eBay and there is an issue with the master output to speakers. Both right (red) phono outputs (stereo and mono) don't send anything - the speaker isn't even distorted - it just makes no noise whatsoever. I've tried swapping the phono leads left to right and it swaps speaker. Does anyone know what this will be? I'm a bit of a novice with this gear - only just bought myself CDJs and mixer recently.

Thanks

Alex