I had one that had gone an inch or two, then stopped. I gave it to 48 hours from initial pip. When I checked it at 48 hours, it was gone. So I had 2 others that were working pips, and didn't want it to happen to them. One was at 36 hours, so I widened the pip, chipped a little of the air cell off, cleared its bill and went to bed. The other was only at 24 hours, so I just made sure the pip hole was open and moist. At 2:00am, I chipped more of the older one's shell off, and the blood vessels looked much better. One was wrapped around his head, but I was able to clear it. His body was stuck pretty good, but I used Vaseline and moistened him up really well. Got up at 5:00 and both had hatched. I thought I was going to have to cull the one that I assisted, it was kinda twisted up, but within an hour or so, it was fine!
Checked the rest of my eggs, all DIS, so I'm done. 3 out of 7 duckies.
I think my humidity was too low for the ducks, but my chicks hatched great, so I think I'll not incubated ducks and chicks together, unless I use another hatcher.
Best of luck on whatever you decide to do. I hate going in too soon, but it hurts to wait too. Go with your gut!