Thanks GoRt!. What a good idea! Why didn't I think of that? I found an old external usb drive, plugged it into the nas, copied the last couple of backups via the nas and then plugged the drive into my stb. It found the backups and I loaded one. I answered all the questions about plugins, etc. Great relief when my favourite channel appeared after a restart!
But when I pressed EPG or menu, etc, the picture shrinks normally to the top left of the screen but the EPG/menu area are completely blank! Luckily I can still just about use the menu via the built-in mini-screen on the VU+ stb... Not sure how to proceed. Could reload the backup now that it's visible again? Or is it a plugin/python problem?