Just an update: It was a setting and the SWCG has been running nicely. I'm slowly bringing the chlorine gen level down to try to get to match the ideal for the CYA (currently 60) but the FC today was 8.
Meanwhile the new pump is silent and wonderful.
I still need to fix the old one. Now the impeller is stripped and one of the switch blocks has a snapped-off mounting ear. But time has kept me from addressing these problems.

I found my pH trending DOWN--surprise! So I added a very sophisticated combination of pH increaser and T/A increaser...Arm&Hammer Washing Soda!