As far as value, the incubator was really inexpensive. I want to say around $60. As far as hatching rate -- not so wonderful. Less than 20% of the eggs from the supplier hatched. I suspected temperature was an issue. The incubator had a huge variance between hot and cold spots: even within the same area it wasn't stable.
Rather than replace it with a more expensive brand for my second try, I decided to hack it with an inexpensive fan meant for cooling electronics. Two small sized fans were placed inside the incubator and there was still enough room for 80 quail eggs.
The results exceeded my expectations: 100% of fertilized eggs hatched within hours of each other and the birds were healthy, energetic and dry. Here's what I did.
I purchased the fans from Amazon.
After spraying the incubator with diluted bleach and letting it dry for a day, I added both fans to the inside of the incubator. The cords are thin enough that they still allow the incubator to close. This particular fan model has three speed settings on a switch. I set the speed to low and set the incubator thermostat to 99.8 degrees (for coturnix quail -- if you are hatching different birds, please check to see what temperature is recommended). Because I live in Hawaii, there isn't much I can do about the high humidity, so I decided I wouldn't worry about it. I ran the incubator dry and the reading on the incubator ranged from 45% to 50% throughout the pre-lockdown period.
I let the incubator run for a day without the eggs and routinely checked the temperature using a probe thermometer through the ventilation holes. I was amazed at how even the temperature was throughout the unit. Before adding the eggs, I sprayed the eggs with 3% hydrogen peroxide, the kind you buy from the drugstore. During the pre-lockdown period, I turned the eggs manually at least 3x a day, opening it just a crack and doing it as quickly as possible.
On day 14, the lockdown day for coturnix quail, I put plastic mesh over the top of the fans, just in case the fan holes were big enough for the birds to slip through (I don't think they are, but you can never be too cautious). I filled a spray bottle with warm to the touch water and misted the eggs before setting them on their sides for lockdown. I filled the reservoir channels with water and added a moist sponge under the large vent in case I needed to add more water later. Then I waited. During this time, the humidity rose to 89% on the built in incubator gauge, then dropped to about 73% within a few hours. I added water only when it fell to around 65% or lower.
On day 17, my camera app alerted me to motion in the incubator (I had put a security camera inside the incubator to video the hatch). Within 3 hours of the first motion, seven of the ten eggs I placed had hatched. I left the hatched quail in for 10 hours before removing them, adjusting the temperature upward to 100.8 degrees after hatching because the probe thermometer showed a lower reading than the incubator. When they came out, they were already dry and quite active. I left the remaining 3 eggs for three more days before attempting to candle them. They didn't seem to have chicks in them, and later necropsy showed no signs of fertilization. So, of the fertilized eggs, 100% hatched and all it took was an extra $20 to buy some fans.