This reminds me of something I learned at a young engineer. I routed many wirewrap wires parallel to each other in a 8085 microcomputer I built. The computer worked, but the internal real time clock function that required some hardware there was a gremlin. I can't remember the exact symptom, but the fact I had crosstalk caused hickups every day or two.

I didn't learn my lesson well enough. Years later I did all the electrical wiring in my house, and I ran some of my circuits right next to each other. Needless to say, when I turn some things on, I get a glitch in a neighboring circuit. I haven't gotten around to drilling new holes in the joists and rerunning the romex.

Excellent trouble shooting. Thanks for sharing.