Hi Moxie and Andi
There is the potential for a poor solder joint on the audio input jack it is something we are taking care of in manufacture but very rarely a board can slip through.
I have marked the image where the issue is. It could be quiet easily sorted with a soldering iron and a touch of solder but we much prefer you to have a new shiny working board than asking you to fix it yourself. ;)
Once again sorry for the trouble this has caused
Regards
Gee