I had five eggs under a broody hen. It is day 21 and three hatched yesterday (all were laid the same day). One shows no sign of hatching and one chick is struggling. The fourth chick started piping yesterday early afternoon (ish), made some progress this morning, but not much since and it has been at least 24 hours. The hatchling is not pecking in the circle like it should. It is vocal and alive, but mom has left the nest with the three others and appears to have given up on it. At what point do I do something?