Bad Hatching

I dont understand it, I have hatched out 4 batches of eggs with no problems so far. I disinfected  the incubator and have left all the settings the same but this hatch has been a nightmare!

As they were guinea fowl eggs I did alot of reading up and set the humidity for 55% and raised to 65% for hatching, last day of turning day 25, candled the eggs and we were good to go. I have a manual turn forced air incubator, I turn 3 times a day and use paper towels for moisture.

Day 28 nothing! Day 29 they eventually started but out of 21 eggs only 5 pipped and were very slow and lethargic, not even cheeping. I left them alone for 12 hours but  had to help in the end.

There is still movement in some of the eggs so even though it is day 30 I have left the incubator running.

The chicks that have hatched I think may have splay legs, I know this can happen when the hatch is late.

Eggs came from a very reputable breeder, anyone any ideas on what I have done wrong,or is this just part and parcel of incubator hatching? 

I hatched guinea fowl using a broody last year and out of 8 only 3 hatched so could be guinea fowl in general  .

Just  wondering how long did you let the eggs rest before popping them in the incubator - I was advised they need longer than chicken eggs.

I was told even when picking the eggs up yourself with guineas they really need longer than this to rest.