Good grief, it's hard to candle an egg with one hand and operate the camera on the phone with the other. The pictures still didn't come out well, but hopefully they're ok enough to see. There is a dark spot next to the air sac (close to my hand) about the size of a nickel. The pictures look like there is a dark strip running the length of the egg, but it's just a shadow from the flashlight. I can still see some veins down there. You can also see where I marked the X for turning. I haven't seen any movement in the egg, and I estimate it to be around 16-17 days or so.
With any hatching egg, for me, if it doesn't stink and you're in dobut, I just let it continue. That said, if it hasn't moved, I might toss it. I have not tried to hatch ducks, but if that were a chicken past a week of incubation, if it wasn't moving, it'd be a gonner. Compare it to one you know is alive and it may become clear if it is a quitter or not.