What about the attachment piece, also mushy? I've had that once in my hatches and I snipped it off after 24 hours and used coconut oil on it. The chick made it but that little piece of cord was pretty dry.
Is the yolk all dried out or is it still mushy? If dry you can snip it off with sterilized scissors. Some probiotics and vitamins would probably help give it a boost, Nutridrench also.