Thanks again VOS. Now lovin the meters to technically check rather then just using trial-and-error.
The only remaining question is what caused the problem. I don't think "water" had anything to do with it.
My current theory is that the dual SWM setup doesn't like multiple tuners on the non-power passing side SWM; or it doesn't like the use of the legacy port on the non-power passing side SWM. Those were the only changes made after the dual SWM setup had been running for many months.
I switched to the power passing splitters based on some searching and looking at other implementations.
I really want to get the 1020a working but need to 100% verify that the current setup works before attempting it again.