I’ve got clucky hens at the moment, 4 of my 7 hens in fact. So I let them sit some eggs, checked it a couple days back and one was struggling to get out. We’ve been breeding chickens for a few years now and I think I’m good at calling when it’s a lost cause.
They typically peck a hole and work their way around the egg. When they make it back to the original hole they can break out. Sometimes it just pecks a widening hole on one side of the egg, the membrane dries and they can’t break out.
For anyone who hasn’t done an assisted hatching, you can’t simply break open the egg, the blood vessels attached to the inner membrane will rupture and the chick will bleed out (ask me how I know

).
It’s time consuming but you need to chip away at the shell, then carefully remove the outer membrane without nicking the inner membrane.
Sometimes it requires a little help then it’ll do the rest. This guy I noticed the evening before struggling so by morning it was running out of energy and the membrane was dry. Eventually I got it out, put it under the hen and a couple days later here it is

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