I forgot to add they have been in an incubator with a steady temp of 99-100 degrees and since Day 18 have had a pretty consistent humidity (we had a few times it dropped) of 65%.
I'm a first timer at hatching chickens. I know patience is the key, but I'm worried about 2 of my unhatched chicks. We've had 11 successful chicks born since yesterday. Today is Day 21. There are two that started to hatch and have quit making any progress. There are two more with zero progress...