Thanks for dropping in. I may have found something:
1. Pretty fluctuating outputs; see the image (the arrows inside the orange shapes indicate fluctuating values; actually i think they all fluctuate, not just the ones with arrows to their left). Input does fluctuate as I move the measuring sticks but not as much.
2. output 5 appears to be bad. See the gray rectangles (output 5 vs output 8). Checked the same setup for outputs 6 and 7 and it was the same outcome as for output 8. 5 stands out. 5 is the presumably dead output that has failed my previous test cable experiment.
I have only disconnected the second cable (5 – 8, COM) as the first cable (outputs 1 – 4, COM) does not exhibit any problems.