After watching numerous videos I was able to discern that the problem was with one of the following: the timer, the heater, or the thermostat. a short time check showed me that the timer was working so that narrowed it down to the other two. Not having the necessary tools to check those two I ordered both parts. Once the parts came and I took out the old parts it was quite evident that it was the heater since it had black burn marks on it. I decided to install the thermostat also since it was only about $30 so why not play it safe.
The whole process went very smooth thanks to the video at you site that shows how to replace these parts. The hardest part was getting to the parts themselves but I was most grateful that at six feet tall I had a top freezer.
Thanks for the help with the videos, schematics, and your chat line that helped me determine which thermostat to use. And even more, thanks for saving us $1,200 for a new refrigerator!