This is Turtle.

Every once in a Blue Moon i will work on a ice maker in a Refrigerator and
was thinking about the hollow ice cubes on the ice maker and what was the
general cause. I had this trouble on my ice maker at my house about 3 or 4
years ago and someone here told me what it was and I fixed it and i have
slept since then and it is starting to do it again , just a little. Can
someone refresh my memory?

TURTLE