Granny, do you have pics and measurements of the fridge and heat coils?
I could make a few suggestions and probably sketch something up for you.
I am sure there are others Sally will enlist to help as well.
its cabinet bator spring heat that threads through the ceramic rollers

Granny I keep finding fridge ones but they all have lights in them.... not sure the heat will not melt that thing https://www.backyardchickens.com/t/714482/home-made-incubator/10#post_9766584