hatching goslings in octagon 10!
i used a brinsea octagon 10. i had a similar problem to you. all made it to the end 2 didn't hatch, 2 did. i have one lovely gosling 2 weeks old now, sadly the other one that hatched didn't make it.
i think this was humidity issues too. even though i had a gauge in there to measure the humidity.
we only really needed one to go with our gaggle, so wont be trying again this season.
have you read pete 55 article about incubation and hatching quite a lot of information there.
did you have automatic turning on yours?
best of luck for next time!
where in glos are you?