I have a broody hen who is sitting on eggs. Today is day 21 or day 22. I hear a chick chirping inside (it has pipped internally) but has not pipped externally. I heard the chirping internally over 15 hours ago. Still no external pip. Could not hear chirping this morning. Candled the egg and the chick looks to be in the proper position. Should I start an external pip or just leave it alone and let nature take its course? I have done many hatches but never one that has taken this long to pip externally. I do not use an incubator to hatch, nor do I have an incubator. It had a large air cell to begin with....or so it looked to me. Thanks!