917. I seem to be able to edit entries now. I did a little detective work, by going back to first causes.
I also contribute to another blog everyone doesn't read (but ought to), Zrharc!. And that blog did allow me to edit posts.
What, I said to myself, said I, was the difference between that blog and this? Nothing. Except, of course, that I redirect the RSS feed to Feedburner on that one.
I stopped feed redirection...and lo! I could open a blog post for editing again! But...the changes were not being committed to the post. So, I tried one post back...the change committed. So I deleted the original post 917 in favor of this one, which I will perforce try to add something to.
And if that works...I've got to decide if I want to live without Feedburner for now.