When temperatures fluctuate in an incubator that is controlled by an electronic thermostat, I hate to say it, but the incubator is placed incorrectly. They must be in an area of the house in which the temperature does not often fluctuate, out of drafts and sunlight. I use a closet for my incubator, and place it on a shelf. I have had very little fluctuation (and it is controllable if it does), and that is with a two year-old wafer thermostat Hovabator. When I first got it, it was even more accurate, from what I recall.
Any incubator can hatch babies, if they have a device for regulating temperature and humidity in some way, no matter how advanced the technology is. It's all about how you adapt to using the machine, your own skills, and tiny variables such as outside temperature, outside humidity, and placement.
That being said, the OP seems to have obtained an incubator set a little too high. That, or her house is a little warmer than ideal. It's really hard to say, but every incubator requires some time to acclimate to its environment. That may or may not involve human intervention.
