After cleaning out the inlet screens the EF persisted. Ordered this to replace the valve set. Ordered on Friday, and expected it by Tuesday. I was pleasantly surprised when it was delivered the next day, Saturday. I was not so pleasantly surprised that one of the three black seals on the tubes to the water distribution manifold was missing, so I just used one of the original ones.
Unplugging the wires to the original solenoid valves required more force than I expected. I pushed and tapped with a screwdriver to loosen them.
The project would have been easier if the shutoff valve at the wall would fully close.