Chirs,

The proper humidity is 50% and 55% during the last 3 days.

Seramas do well at 45-50%  and after they have pipped, anything above that is ok and preferably very high if the incubator keeps getting opened.  If you have a hygrometor, you will see that whenever the lid is removed to turn eggs, humidity drops instantly to as low as 20%.  When eggs have pipped, the holes in the egg allow that dry air in when the lid is removed and chicks can still get stuck to the shells.