I had a similar problem.
Does it matter if your couch slide is in or out?
Mine stumped everyone until I figured out the slide position vs shore power blowing.
Coach gfci wouldn't blow, coach breakers didn't break, surge protector didn't break, it was always shore power that failed.
Mine was dead short caused by the slide pulling a bare wire.
It worked fine always until the last half inch of putting the slide out, and sbore would blow.
If the slide was already out when plugging in to shore, shore would blow.
We would put the slide in and everything worked.
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