Thank you Hans, Alexandre, and Jan for your quick response.
update-grub2 has enabled booting to all (2) of my OSes :-)
Now the prospect of massive, messy recovery is gone. I like Jan's idea
of a small "boot/rescue" OS, especially if it could be on a USB flash
drive. Something to work on later. For now, it's back to the pile and
the bean counting.
Debian was a pleasant surprise when, with no fuss, it:
Found my old HP 3050 printer
Connected to my ISP
Streamed audio
Browsed the web
I think I'm going to keep it.
- Dan