From last time I’ve now managed to get some new IDC headers to replace the broken ones, so went about reconstructing the ribbon cable.
I also gave up on the idea of getting an A-gauge patchbay and soldered in the aux sends to the back of a 96way bantam patchbay as shown here:
as there was only one 0V reference I had to get a wire and bridge it across all the other connections.
I also wired in 8 jacks to feed back the signal into the mixers inputs. I decided to leave the connections open too, although I considered having them normalled (see this article for patchbay configurations) which would be mental (all signals would be feeding back all the time).
Now to fire it up again and see if there is audio…
Unfortunately I’ve only got 2 bantam patch leads (this might get expensive to remedy). But running 2 channels and 2 auxes it sounds like this (go to the end for animal sounds):