Last I posted, I felt I was hitting a pace. I managed to sustain than, even with an inevitable weekend break, & with all the crazy intensification of activities that comes with the girls' end of school. I began with a printout of my "base material" – lecture notes – and a legal pad, and started rewriting away. A couple of days in, I hit a bit of an impasse on one section; I couldn't find a quotation I needed, I seemed to have lost the thread of my argument, etc. So I stopped that bit and jumped forward to a later section, which breezed along quite satisfactorily. Eventually, I returned to section one and blocked it out to my (at least for now) satisfaction.
All this, mind you, on paper, pen & ink. I'd keyed in the first couple days' work, but hadn't printed it out. This morning I keyed in everything I've done so far – something over 5000 words – and just now I've printed it all out. I'll edit & mark up the printout, and continue writing towards the end of the essay on paper. I figure by this coming weekend I should have a full draft ready for the multiple revisions.
I know it all sounds arcane, but at the moment it's working.