Every time - except the very last time - I have assisted, it has never ended well. Granted, it was all with quails. The chicks usually ended up with super long necks for some reason (maybe I waited too long?) or curled toes. Within 1-2 days they got lethargic and died . Otherwise while opening eggs a couple days past hatch due date to check the fertility on the eggs I used, I will admit, there have been a few that were still alive, and though trying to be careful, I have broken the membrane on accident before the blood was entirely absorbed and they bled out - NOT pretty and makes you feel super crappy. Just leave them. If they don't hatch, maybe that was nature's intention. I'd rather feel like, "maybe if I had helped they would have lived" vs. "maybe if I had just let nature take its course they would have lived". Either way it's sad.