Yet another issue with gear for me, the problems keep on coming!

Saw Jason Isbell Friday night, running 4 channels...everything was fine for an hour or so then I looked at my deck and channel four levels were pegged. I went to turn down the trim and when I touched the outer trim gain, the gain settings went haywire. It was shooting all over the map on channel 4 but it was registering like I was adjusting the inner knob - where it shows the fixed gain selection. So somehow the outer trim pot was impacting the inner gain setting. Anyone experienced anything like this?
I tested it again at home yesterday and it replicated so I'm certain it's a deck issue, I went from B Format to stereo out on the Soundfield with the same results...so different cables were used.