Pirate Audio headphone - can you switch off channels?

The reason I’m asking is because my Pirate Audio headphone board has stopped working on the left channel. I’m trying to find if there is some configuration setting I’ve changed accidentally or some software corruption that could cause this. I’m getting the same problem with vlc and alsaplayer. It was working fine but when I started it up yesterday the left channel wasn’t working, and it’s never worked again since then.

Did you try another pair of headphones; or reinstalling the software

I’ve tried other headphones with the same result. I’ve tried the headphones on my CD Walkman and they work fine. I’ve tried changing the gain switch I haven’t tried a re-installation yet but that’s the next step.

I’ve tried re-installing, I also tried writing a fresh Raspbian installation over the micro SD and reinstalling everything from scratch, and I’ve tried putting it on a different Raspberry Pi, still nothing on the left channel. It looks like this Pirate Audio board has failed. A pity since I had just created a useable version of the music player I was writing for it.

Is there any warranty on these things? I’ve had it for a month now so if there is it’s probably run out.