I have an LG and they can be a pain to get set with the right temp! Mine is forced air and I have had several hatches in it, including a 100% hatch on my own fertile chicken eggs! At most with the shipped eggs I would get 1 or 2 per dozen, that was very frustrating. I couldn't figure out if I was doing something wrong, the bator was bad, or if it was shipping. With my 100% hatch of my own eggs, I think it has a lot to do with how they are handled in the mail. So good luck with yours!
I have a Spot Check thermometer
http://www.brinsea.com/products/thermo.html and love it! It is accurate to +/- 0.2. With it I have determined that my incubator also has "hot spots" and "cold spots". I have one corner that I don't put any eggs in because it is a whole degree cooler than the rest of the bator. It is on the farthest corner from the fan and opposite the auto turner motor (which also puts out a little heat).
I found it best to put some eggs in the incubator (ones you aren't hatching) when you are trying to get the LG to the right temp because it seems the eggs will absorb some of the heat and will help keep the temperature a little higher in the bator. I learned this after getting the bator to the perfect temp then putting my eggs in only to have a spike the next day of a couple degrees. It is very stressful trying to lower the temp to what you need it to be WHEN you have hatching eggs in there.
Hatching is also very addictive, I thought I would only hatch out a couple here and there just to keep my flock going but now
it seems that I am hatching out a LOT more and I am thinking about getting a Sportsman!
With the LG during lockdown what I have had to do to get the humidity up in the bator was to add three sponges on top of the wire floor on one side. I have a partition made of hardware cloth to keep the chicks off of the sponges. The sponges are within easy access of one of the large plug holes so that I can easily add water when needed without opening the bator. I have a large syringe with aquarium air tube attached so that I can put the water where I need it to go. Sometimes I only have to wet one of the sponges other times it is all three in order to get the humidity where I need it. Even for the first 18 days I dont open the bator except for candling, I just use the syringe and tube to add water to the channels in the bottom of the bator.
Good luck with your hatch!!