That's what it looks like to me, adjusting the crop.Is that what she's doing? When she sticks her head up in the air and opens her mouth real wide? We always feel her crop before feeding her to make sure that it's empty and it always is and she is still pooping a good bit.
She also "preened" her neck/toward the crop right after an adjustment, so I wonder if it's turning sour or she has some thrush and it's itchy. I've had hens with sour crop that would make a preening action right at the crop and of course the adjustment motion as well.
There's no lesions or white/yellow pasty or mucousy material inside the beak or throat right?
Her breath smells o.k. - no bad or offensive odors?
Now, if she's suffering something neurological or has Marek's then it's possible the actions could be related to those, but ime, it's something to do with the digestive system.