In October, I replaced one of the sensors behind the panel inside the refrigerator (I don't know what that part was called. With the refrigerator defrosted, the temp came down and stayed that way until January.
In early January, the ice started building up again. This time I replaced the thermostat and thermistor. After defrosting the freezer and removing the trays, screws, and back panel, I disconnected the wires from the back and replaced the sensors with the replacement sensors.
The video on the website made it easier, I just followed that and put everything back the way that it was.
It's been over a week with no ice yet.