KRK Rokit speaker issues

I’m having issues with my studio KRK monitors. They seem to both work when I connect them to my laptop, using an aux output on the mac to 2x rca input into the speakers. However when I have an rca output from my device (TV, DJ decks etc.) only one of the speakers works. Can you provide any guidance on this, and if it needs a repair, are you available to do this?

Many thanks for your help!