DJM-450 Channel 2 not outputting sound

Hey there,

I have a DJM-450 which has been running smoothly for a couple of years now. However today during a mix, the second channel abruptly cut the sound from the incoming signal from the 2nd cdj. The left deck and channel were still outputting fine sound however the right channel wasn't - despite the djm showing audio signals from both on the display. 

I've tried using a turntable through the phono channel on channel 2, as well as updating drivers + factory reset etc; but i still can't get any sound being output through my speakers from that specific channel. 

I have also tried to use different rca cables but still no luck. 

Does anyone know how to fix this or is it a major fault? 

Thanks