I'd have a look, there's probably something preventing the spud from moving at this point. What I do is open the large aircell end big enough to shine a light in and look at the inner membrane and veining.
Big bright veins and a moving chick suggest one running late. Damp the membrane very carefully - don't we it, or get drops into the shell. Cover most of the hole with tape or a cling wrap and wait a few hours, check again, the veins should be smaller or not apparent. You can start to assist then.
A dry white or gray membrane, with no or few veins is probably stuck. They've often pipped into the aircell but gotten no further.
I get a lot of unhatched eggs from under broodies like that. The little bugger needs help out for some reason. Often pullet eggs do that due to too little room and/or a larger chick.
