Your box is wired correctly. If you haven't done the following, do it just to make sure everything is right.
Make sure the TRS output jack on the guitar and the TRS jack/cord are wired exactly the same as that input TRS jack in the box.
In other words, make sure the tip goes to the tip of the output jack in the guitar, the ring goes to the ring in the guitar, and the sleeve goes to the sleeve in the guitar.
If that's all fine, you really should follow the signal path from the output jack of the guitar to the OBEL switch and make sure it is wired correctly. You have to know for sure that it's all correct. It's a simple circuit, but one wrong connection causes total failure
The problem that is occurring when changing from battery power to house current could just be happening do to the OBEL problem, hopefully!
First show: 1973
Last show: 1994