Thank you for getting back to me.
I have tried a different power source but, no joy. I am powering it from a 5V usb to the df13 ports (I tried both). This is sufficient to power the device through the micro usb port so I reckon the issue is with the df13 port(s)?
I also having an issue with these ports when trying to get a serial stream from them which I have described in this post.
Given the age of the Reach unit, the circuits may have reached the end of their life. I would like to try installing the older firmware as final attempt but, as far as I understand, this isn’t supported?
If I happen to find a fix, I shall update and hopefully in the future I can find an excuse to break the piggybank for a new set 
Thank you for your time.