How long should you let eggs that are moving but not piping go?

[alln7220]

I had 10 eggs in the incubator. they we due to hatch monday the 7th. only 2 have hatched. one hatched yesterday and one today. the others have been moving since monday but no piping. we got these eggs through ebay. we have hatched our own eggs before with out a problem. but this is something new. should we try to pip them since they are 4 days over due or just see what happens? i just dont want them to die.
hatchless and confused