I must admit I had one last year that pipped outside the air cel and we helped him hatch out. At first we were so excited that we got him out without damaging him, however over the course of his good but relatively short life he presented with a number of issues: a curled toe (which we were unable to fix), spraddle leg (which we did fix), impacted crop (which we also fixed), twisted neck (which we also fixed). After all these problems, about 2 weeks ago he was the only one in the flock who finally succumbed to a virus (the others had it but got over it). I have heard of people intervening and the chicks being the same as any other, though in our case either something wasn't quite right ever and (with hindsight) it might have been better had we not intervened. It's a hard one, everybody has a different philosophy about this, you do what you think is right at the time but hindsight is a wonderful thing and next time I will try to intervene a little less! Best of luck with your hatching, it's great to be involved but I know too well how stressful it can be