I added back an RF choke (“big ugly balun” style) on the EARCHI antenna and seem to be able to get all of the 40m and 80m bands now. SWR is a little higher at the bottom of 40m, but still well within the internal ATU’s range. I’ve been able to work 10m, 15m, 17m, and 21m, including some great DX to South America on 10m yesterday.
If I can get 20m back, I’ll declare total victory across the board.