We ended up getting four chicks from the eggs we purchased.

We purchased 12 eggs, here are the stats:

• 2 Infertile (Removed at 10 days)
• 2 Very early death (Removed at 18 days)
• 4 Late death (Removed at 20 days)
• 4 Hatched (one on day 21, two on day 22 and one early on day 23)

It appears that the ones which hatched were nearest the temperature sensor, so maybe we had a problem with hot and cold spots (The incubator was fan forced).