I just couldn't help it anymore - I opened the incubator, even though egg #3 hadn't done anything yet.
I was sitting there, watching all the egg-white goop drying onto sticky-chick, thinking "It's going to glue his bung-hole shut!" So, I took them both out and put them in an old glass fishtank on the floor near the incubator, so that egg #3 can still hear them peeping. I cleaned up sticky-chick as best I could - he was all dry and crusty, with pieces of eggshell glued to his neck, but not five minutes after I scrubbed his butt, he produced a lovely, big, green poop for me.
He's still all crusty and cakey and he looks just awful, but he took a big drink of water late last night, nibbled on a few starter crumbles, and they've both been contentedly napping since then.
Here they are - I think they're both blues! The first picture is before I cleaned sticky-chick up - no, he's not wet in the picture, it was all hard, dried, shiny egg white that had actually glued some of his toes together:
Here they are again after I tried my best to clean sticky-chick up (which he protested quite vigorously):
After I opened and closed the 'bator, the humidity bounced right back up into the sixties within a few minutes. I heard egg #3 peeping again this morning, and now he's made a tiny little crack in his egg! He hasn't done much since then, but egg #3 was one of the larger eggs to begin with, so it makes sense that he should take a bit longer.