Mary, I assist quite frequently since Calls have much shorter necks and bills than other ducks... I currently have over a hundred and almost all of them were assisted...
Is this your only egg in the bator?
It sounds like he's getting closer. Just tap on the incubator, no reason to open at this time. Keep interacting with him when he's awake, but when he's asleep, let him nap. He needs his strength.
Next step he SHOULD start working sideways. I fear that he's a bit stuck and may not be able to rotate, but if he is still doing that pant/gasp he still needs a little more time. I wish I had a video of a ready chicks and poults that I could share. Like knowing when a tomato is ripe, you learn the signs.
Agreed, I think he can be declared stuck. Those yellow crystals indicate that he is going to be glued in with what is half-jokingly referred to as "gorilla snot" that when it dries is like epoxy.
Ravyn is our waterfowl specialist. But when it's time to help, you will need a bowl of warm water, a dry towel, a warm wet towel, a warm draft free place (under a brooder lamp is fine), a comfortable seat and a table or counter to work on. Not stone or tile, it's too cold.
Please read this article first http://www.backyardchickens.com/a/step-by-step-guide-to-assisted-hatching but remember that what you see needs to be your guide. Use your own judgement to determine whether to stop or proceed.