Do yourself a favor, please check it out as mentioned earlier before you get caught up in distraction/analysis because the symptoms are seemingly 'complex' for a very very basic issue of an open/intermittent....
You have to remember that these machines are totally dependent on scanning and distributing analog control voltages.... you sabotage that and the whole synth goes out of whack with all kinds of oddities. Otherwise, looking at it with blinders, I would have been faulting the effects unit, the filter unit etc. - again, can't overstate it, that one point was the crux of the whole 'gremlins' issue.