Broody mom- my hatch was a success so far. I had 10 eBay silkies that made it past week one hatch, and also 3 ducks so far. Still waiting on two more ducks and 4 polish eBay eggs which are due tomorrow.
At this point I would personally dive in after the ones I thought were maybe alive at day 21/22 and no pips. Here is a great thread on assisted hatching http://www.backyardchickens.com/a/step-by-step-guide-to-assisted-hatching
Basically you pinch tiny bits of the air cell carefully with flat tip tweezers and whatever you do don't nip past the air cell or hurt the membrane. Then you dab the membrane with warm water and keep it very humid in the incubator.
Not sure if it's something you would want to do but it is a last resort option sometimes. Did it on my first duck and it turned out well.