Well it did rain, about an inch, so I didn't open the box. But, with both outlets completely covered, no GCFI trippage. That doesn't really mean anything because before it would trip the next day after a big rain. More to come in this saga.
Today, even though it was threatening to rain, I open the outside (formerly burried) box. I wanted to put some better screws holing the cover because at least one was stripped out. I was surprised at how much condensation was on the inside of the cover. I did reposition the wire nuts so the open end faced down. I think I am going to put a vent on the cover. Maybe a 1" plastic pipe coming up, 90 degrees to the right and then 45 degrees downward. A piece of screening in the pipe would keep bugs and critters out.
Underground installations are considered wet locations because they all fill with water over time. Get some direct burial rated splices like they use on well pump wires and eliminate that as a suspect.
Next update. It rained quite a bit on Tuesday, no trippage on Tuesday night or Wednesday. On Thursday, just a drizzle in the 3AM area ... Thursday night, tripped! I'm ready to remove the GCFI and go 'illegal' with a regular breaker. As this never happened when I had the original dead front GCFI just below the breaker box, I think I will exchange the breaker for a new one. I might also try the old dead front GCFI again to see what happens.
Just call an electrician. Namely the one who put it there those many years ago, OK?.
If you want to make a worm chaser you could move the GFCI protection to the first "outlet" outside. That is still legal, even on the 2020. They did require GFCI on all outside "outlets" (including utility buildings) in the 2020. That includes lighting outlets. (light fixtures)
Actually, I did it so I need to fix it.
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