Update and resolution:
The new TL900 turn signal came in (which I mentioned on another post). Very hefty, and appears very well made.
However, I didn’t install it.
I decided instead to mount the second switch from KW, which I had before the TL900 came in. We wrapped a rubber hose around the steering column as an insulator and the thing is now working.
The reason I did not use the TL900 is that my bill at the auto electrician was climbing astronomically. So, I went straight to surrender to save some $.
Like the first switch, KW quickly did a refund. So, I went through three of these switches before we got one to work (2 from KW, 1 from Amazon).
My guess is that the Chi Coms are slipping on the quality of their work…
Thanks again, all, for all your advice. I’ll reorder the TL900 (as you suggested I get, Russ) if this latest fix fails.