How long has it been since she hatched?
The navel has not closed, that's what you are seeing. If she's the last one and it's been an hour or so, you can take her out, apply some Bacitracin or triple antibiotic ointment to the navel.
Put shallow coffee or tea cup inside the incubator, line it with a paper towel, put the chick in the cup to keep her "contained". This allows her to move and push while hopefully the navel closes, and it keeps the navel cleaner (not dragging across broken shells and incubator "goop"). Close the lid on the incubator so she stays warm.
She will peep her head off, push and carry on, that's o.k., she'll also sleep a lot, then wake up and carry on some more. Leave her for 6-8hours, then see if the navel is closed up.