I had a similar problem with my sixpack where one of the relays wouldn't
quite activate when I was running the sixpack from a nominal 12V
source. Jay was very helpful and told me that the sixpack really needs
to have a full 13.8V or slightly more in order to function properly.
I had an old 15V wall wart supply from an ancient laptop that I put into
service. This did the trick.
Not sure if you are having the same problem, but thought I would mention
it to you because the symptoms I was getting are similar to what you are
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