Ok!
It is 72 hours since internal the pip, 48 hours after the safety pip with the chick still alive, peeping, moving, but no external pip of their own. I have opened the air cell and the membrane is quite dry. Using coconut oil and a tweezers, I worked the part of the membrane that no longer has active blood veins back from around the chicks beak and can see its butt faces the air cell with its leg tucked up and around, past it's beak and over its shoulder.
I am going to leave the chick to rest more and warm up but it is no longer yawning or making eating motions. So hopefully the yolk is fully absorbed.
The picture definitely looks scarier than it is due to the shiny-ness of the coconut oil.
My only concern is that it is quite hard to tell what the inner membrane should look like when it is no longer active with blood supply. My biggest worry is to start a bleed.
Any advice is greatly appreciated!