When setting eggs of course do not chose the cracked ones. Sometimes eggs get cracked after setting. If this happens under a hen, she will eat the egg, and possibly the others as well. It is best to get it out from under her. If you still want to hatch that egg get an incubator, in fact since thing happen, almost best to have an incubator on hand in case of a cracked egg or the hen stops being broody. I fix the egg by putting nail polish on crack, (unless the chick in egg is fully developed, the smell should not bother the embryo) I chose nail polish over wax because I am more afraid of what hot wax would do, but it is everyone else's chose. If you have repaired your eggs keep an eye out for it day 12 because if it is going to explode, that is when most do it. Good luck with your eggs.
Side note: currently have an egg with a dent and nail polish on it, day 11, but the dent is in air cell part of egg, very small, no oozing happened.
Side note: currently have an egg with a dent and nail polish on it, day 11, but the dent is in air cell part of egg, very small, no oozing happened.