Don't shut up. I like you! And so does everyone else. So, we will get ticked if you are quiet.
The chick can stay in the incubator up to 72 hours. Ideal is more 48.
Eggs 'can" hatch up to day 28. Give it two days (day 23 at least) and then start to get worried. Nature is unexpected. I don't feel comfortable with the opinion that a chick pops out on day 21 without fail, or it is too weak.
I am sitting here, pondering how to make it comfortable to be in the jet tub. Maybe pretend I am in the world's best sauna too?
X2, I've found that the ones that hatch a day late usually hatch the healthiest. If I run a higher temp and have them hatch on day 21, they have open navels. Day 22 hatchers are clean, quick, and healed. I'm thinking that's because I have an insanely fast pip to hatch time- Sometimes only 8 hours.