If your using a styrofoam incubator in a cool room, that may be your problem. The condensation can be a result of cooler air getting in slightly causing the water build up.
For got to say that to you but temps are a major reason why you get water build up as well. Removing The press n seal will help minimize this but you need to get the bator in a 70+ room with that type of cooler.
I incubate at 88.6 with a herpstat, not sure what your using but most on off type t-stats cause a lot of fluctuations in cool houses and theres where sweating of eggs start and or box condensation.