Well, they didn't keep working, as things turned out. No help at all from Userland; no response to a help posting titled "Upstreaming failing for nearly two weeks."
Steve Hooker kept insisting there must be something wrong with my
files. Checked with FileBuddy, and low and behold, key files showed no
"file type" (should have been "TEXT") and wrong creator ("text" should
have been "ttxt"). Not clear how they got that way, but fix seems to
have worked. Let's see if it holds this time.... If it does, blogging will resume.