The output jack on my Thumb seems to cut out when I push the plug in a particular direction (towards the headstock) so when I'm playing it occasionally cuts out. It's not a massive problem, just a little annoying. Is there anything I can do to fix it without replacing the jack? I have an appropriate sized wrench but it is very difficult to remove because the nut seems to be recessed into the wood slightly in the cavity so I can't get the wrench in properly. See what I mean about the nut?