He's getting thermal shock. That's when the cage is cold but you have a concentrated heat source. They'll stay under the light and get burned but still be cold.
If you are using a screen cage, you should cover the back and sides to hold in more heat.
There have been reports of premature hatching when the eggs are exposed to bright light. These new LED flashlights are extremely bright. I wouldn't chance it, especially this late in incubation.
Digital with accuracy to 0.5 degree F. Customizable settings for the set point plus settable hysteresis to allow for a sweet spot where the heat and cool loops won't fight each other. Possibly an alarm for over/under limit.
I'm considering putting together a kit to convert any insulated box, like a small old fridge, etc. into an accurate reliable incubator that can heat or cool for less than $200. Would there be any interest in something like this? There would be some DIY involved, but not too much.
I like them a lot! At one time I was looking to work with them. Not sure what you are asking for them, but my previous attempts to get a pair or trio were more than what I was willing to pay.
I've always said not to use them because they need to cool down at night. Whether or not they can see it, I don't know for certain and I can't recall the article where it may have been mentioned. But if the choice is to provide a light that is a totally unnatural spectrum, or one that puts out...
IIRC, they can see the higher UV spectrum that we can't, but they do sacrifice the lower end of the visible spectrum. That's why they sell the red bulbs for night heat.
Sounds like he likes the 100W better. They should not spend all of their time under the basking bulb, that is a sign that they are too cold.
Obviously when warmer weather comes around, you'll have to reassess.
Replace the red with a white. They don't see red light and their instinct is to bask under light they can see. Plus you want more light in the enclosure, not less. Makes it harder to hunt their food.