Hmm. Not fixed. At my cottage, it works fine. In my garage at home, it exhibits the problem. The only difference I can find is that the voltage at the cottage is exactly 240V, at home we have 128V on one leg, and 123V on the other, about 250V phase-to-phase. Would that do it?
Additional data: It seems the EVSE board is triggering the contactor on and off, I see voltage on the relay connector when the contactor is closed, none when it is open.
I have it inside again to dry, and will know for sure in a day or two.