I had one waaaayyy worse than that I repaired with nail polish (clear) I was on day 16 when it was damaged. I think I like polish because heat and humidity cant hurt the dry polish- it wont melt off, rub off, or dry and flake off. It also gives better control during application and its pretty thin, but does a good sealing job. Those are just my opinions though.... I also have a feeling the polish does not have a porous composition and therefore is less likely to let in bacteria that could damage or kill the developing chick. My egg hatched and she is laying for us! Good luck with whichever way you go! If you do a search, I posted pics of my egg, under- Cracked eggs can make it. I think its in the hatching eggs section. Whatever you do, make sure you dont put too much of anything, espeacially where the chick will pip through, you dont wanna make its job any tougher!
