Sounds like you're in need of some thermometer and hygrometer calibration
It's fairly easy to do.
To calibrate your thermometer, fill a glass with ice and leave it out to melt until the glass is half water and half ice. Put your thermometer in the glass, give it a couple minutes to get to temperature, and check it. It should read 32 degrees Fahrenheit. If it does, great! Your thermometer is accurate and you can use it to set the temperature in your incubator.
If it's not right, not to worry, you can still use it. A little math is in order. First, you need to find out how off it is. For example, if it says 33 degrees instead of 32, you know it's reading one degree higher than the temperature actually is. Therefore, when you put it in your incubator, you want it to read one degree higher than the temperature your incubator is supposed to be set at. So in a forced air incubator, you would want it to read 100.5 instead of 99.5, because when it is reading 100.5 degrees, it means the actual temperature in the incubator is 99.5 degrees.
The same is true if it were reading low, so for instance if the thermometer reads 31 degrees instead of 32. In this case, you would want it to read one degree lower than the temperature you need your incubator to be, for the same reasons as above.
To calibrate your hygrometer, you can use the "salt test". Take a teaspoon of salt and put it in a bottle cap or a small cup and add a few drops of water to dampen it. Take this and your hygrometer and put them inside a sealable see-through container. A Ziploc bag can work as long as it seals well. Let it sit for six hours and then check what the reading on your hygrometer is. The hygrometer should read 75%. If it doesn't, you'll know it's off, how much it's off, and you can calculate what the real humidity is by how off it is.
