After 4 months I seem to have finally found the problem. I bought a multimeter after a suggestion from Old Sarge on the forum. While testing the second wire, another of the connectors just fell off. This is the third one that just fell off seemingly for no reason. After replacing it, I performed three almost identical two-hour tests just like the attached screen shot. I don't know if it just my bad luck with this unit or not, but the wiring seems a bit flimsy. Just my thoughts for future upgrades and repairs.