To be honest, I haven't used a Hova-Bator but the Corn Snake Manual says a couple of things.
Do you use sphagnum moss or vermiculite? If you use sphagnum moss then make sure it stays damp. When you are setting up the incubator, soak the moss in water then ring it out and place in the incubator. When the eggs are incubating you should regularly check to see if the moss is drying out, if so, spray some water over the top of the moss but be careful not to wet it too much.
If you are using vermiculite a small portion of the eggs should be showing above the surface to enable you to check on them and to make it easier for the hatchlings to get out. You should mix a certain weight of vermiculite with the same weight of water and place it in the incubator. You shoud then place a sheet of paper over the eggs to stop them from drying out. When you need to check on the eggs all you have to do is pick up the sheet- very simple. Whilst looking at the eggs you should monitor the dampness of the paper; if it is too dry add water to the EDGES of the verminulite as to not damage the eggs.
You probably already knew all of this but I just wanted to be sure. If you are doing these things and your eggs still continue to dry out then perhaps you should re-invest in a more suitable incubator.