Well I have done quite a bit of clean up and looking and I've got to think somewhere there are at least 10 missing, so one clip of sets... I can accept that I guesstimated wrong when I made some extra but it is interesting that having made the correct count at some point that 10 are not there. Yes, I did check the trash bag near the sewing table -- sometimes stuff falls in there unnoticed.
Sewing table looks better than it did, and at this point it will be faster to remake than keep looking. I know, of course, as soon as I make the replacement units I will turn around and the missing ones will fall on my head. Small price to pay for getting towards completion!