I would scrap it. Six days behind is a lot. I have heard the occasional crazy day 27-28 hatch story but by golly are they rare! And they are typically with just a slightly lower temp over a lot longer time slowing them down a little over a long period instead of a lot in a short time. Many times the chicks out of these hatches are just weak, too... Not deformed but not really healthy. Lots dont make it. So I would scrap.