I am chagrined to report that I had to make the universally required three trips to the hardware store to fix the drain mentioned in my previous narrative. The first trip to get the required part resulted in no parts at all. I decided that because the particular store that I went to had the part only as part of a larger assembly that I did not require. The second stop was at a store that had no such part in any shape or form. It was at the third stop that I found the part that I needed only to get it home and discover it was too long to fit in my sink. That is, of course, why God made hacksaws and that resulted in a successful repair job.
The three trip rules remains unbroken.