I don't have an answer for you, I'm in the same boat. Had three chickens eggs pip this morning and nothing's happened since then. I've read it takes a lot of work to break out of the shell and they take lots of rest breaks in between trying. That's probably what's happening to both of us.
personally what i would do, and what i wished i had done with my last hatch is poke a small hole in the aircell end of the pipped eggs. i had one pip and then suffocate from not progressing last time and i was heart broken. the only thing is.... don't keep helping! i helped too much this time (i was really anxious after last time) and i ended up helping too much. now i have a baby duck out with his yolk not fully absorbed. he looks like he will make it, but its pretty darn iffy. its a hard hard lesson i wish i hadn't learned the hard way...
DO NOT HELP! I know it's hard, but if you help you could end up killing the ducklings/chicks. Do a search on here and I'm sure you'll find all kinds of horror stories from people that have "helped" and ended up killing the hatchlings. Hang in there and be patient
Yep, just take a tiny peice of shell off where the pip is to make sure it gets air while still in the egg. Not too much for it can dry the inner layer to the chicks feathering. just enough so you can see the beak.
It's been raining here for two days straight -- the humidity is higher outside the incubator than inside the incubator...
I have been surprised by the speed with which my current batch is hatching. Some pip and sit for 12 hours. Then in what seems like minutes (but is probably an hour or more) they zip all the way around and emerge. Some pip and hatch in a hurry, too. I haven't noticed any that get halfway round and they wait.
Anyway, the short answer is do your best to let nature take its course.