I had to replace one of my incukits because a button broke (the company was awesome and sent me a new one). I added some sealant between the incubator lid and the incukit and that helped a little.
I still couldn’t get the humidity above 40%. So I added plastic over the controls and screen as well and now it is holding at 65% with all wells full. I just moved 4 eggs into lock down in this incubator.
My other Franken-bator is holding at 45-55% if I keep 3 wells full.
I did some thinking and I think the temp spikes happened when the upstairs hallway that I am keeping the incubators in got too hot. The gas heater we have up there has 3 settings, low-medium-high and it doesn't shut off when the room gets hot like our downstairs heaters do. So even on low, it gets quite hot after the heater has been on a while. Unfortunately, I need to turn it on tonight because it is going get in the mid 30s tonight and the incubators are already struggling to maintain temperature.
Room temp definitely makes a difference.
Most incubator mfg say room should be at least 65°F,
I have to bump up room temp, luckily it's thermostatically controlled.