I go home soon (YAAAAAY!!!), so I went looking at my sales, and yes, they are clearly slowing down even more, despite the fact that the book now has 13 (!) five-star reviews and is now up to a 3.9-star average.
Which, as an aside, I think points to a limitation of those algorithms. I think that, in a perfect world, the fact that there's more data out there now about what kind of person REALLY likes the book should trigger more outreach to likely buyers. But the algorithms seem instead to be very reliant on momentum, so each slowdown in sales begets a further slowdown.
Anyway, I had set all the Facebook ads to run extremely cheaply since I wasn't going to be able to pay attention to them, and sure enough, very few people have seen the ads and almost no one has clicked. Which is far preferable to getting hammered, but since I shall soon be in a position to actually pay attention to the ads, I bumped up the per-click bid a little today.
I also realized that I never did a Kobo ad for Facebook. Gotta get on that (and fix those links) when I get home....