Speaking from some recent trials and tribulations with this incubator!
Here's what I learned from my first 2 batches of incubating eggs this year with this model:
1. Temperature and humidity are SUPER important. You will need to calibrate your thermometers and hygrometers. Definitely use more than 1 of each to make sure and NEVER rely on the incubator temp and humidity as both of my bators were off.
2. I only filled TWO water channels for the first 18 days. Filling more than that made the humidity too high and drowned my first batch of eggs.

Again, humidity is important.
3. If it is "still air" it is recommended to set the bator at 102-103. Sounds crazy, but just check what the temp is with your other thermometers that are in the bator.
4. Monitor humidity! With my 2nd (successful batch), I ran out of water in my bator and one of my pipping chicks got shrink wrapped. I had to assist. It was so stressful for both me and chick. A pipping chick NEEDS humidity.
5. You do NOT need both red plugs in. You need to circulate air, so make sure you have at least 1 out. Take them both out at day 18.
I used the still air 9300 for first batch (0% hatched). Made lots of mistakes (see above) but went ahead and bought the circulated air bator for 2nd try. Second batch... (100% hatched). I don't think it was the bator, but my experience. I hope you can learn from my mistakes! Good luck, and keep us posted!