If you see an internal pip and it has been awhile, I would external pip him at the air cell artificially. Serama are delicate, perhaps weaker than other chicks, and I've had seemingly healthy internal pippers die without pipping externally. Then it is a matter of assisting the hatch as usual, this guide is good. I've had some chicks come as late as day 22 heading on to 23, but once that internal pip is done it is a race against the clock! If it hasn't internally pipped and is still moving, all one can do is give them time. I have heard say of artificial internal pipping before, but there's no way to know when it is an appropriate time to help, and you risk killing them as easily as helping.
I hope they make it for you! I know you've been wanting a serama for awhile... Here is Chip, a lone hatcher from day 22, to give you some hope! He managed to get out all on his own even though it was my first hatch in a crummy styrofoam incubator that had mad temp fluctuations and weird humidity problems.
Edited by Skink - 9/24/15 at 10:27am