To my surprise, the one egg that hadn't hatched was gone.
I pushed out all the feathers and wood chips -- all nice and dry -- and closed it up again.
I will put in new wood chips in early October and hope for another great season.
I will keep an eye on the inside of the box in the meantime, just to make sure squirrels don't try to move in...
Damn those squirrels!
Since I got the video cam to monitor the nest, Mrs. Ace has laid 19 eggs; 18 hatched and successfully left the box. What happened to the unhatched egg this year is anybody's guess.