The pump was running fine, the suction-type pool cleaner was working fine, the heater pilot light lit up easily (after I remembered to turn on the main gas valve). Then,
The pump overheated (I am guessing, don't know this for sure)
Since the heater had been on for a couple of hours (that's why the sun dimmed a bit?), I figure there was some boiling followed by a partial vacuum
A hose collapsed.
Well, I hate doing plumbing, but Suzanne and Emma and Jeff were due Sunday, so off I went Thursday evening to get parts. Replaced the collapsed hose. Tested it. Leaks everywhere, namely,
The heater end of the replaced hose, the heater manifold to hose clamps (minor drip that was not there before, both inlet and outlet connections
The solid plastic pipe to the salt / chlorine generator had a bend (vacuum + heat)
So, after a search, I found a store stocking the heater gaskets $70, and installed them, got more parts, had a beer.
Today, I attached a quick-disconnect union to a cut-back pipe to the salt machine, replaced the plastic screw-in adapters to the heater, replaced some of the solid pipe with flex, and tested.
Yep, a tiny leak at the flex to plastic hose. Cut it off right at the fitting. Used the spare fitting (credit to Dianne who said, "buy double, take back anything you don't use, assuming there will be anything to return...), reinstall all, and test.
No drips whatsoever.
One two dollar fitting to return..
May turn on the heater later today, but somewhat scared, don't you know?