Product review (5 stars): Easy to diagnose, easy to fix
If you know how to open your freezer door and use a screw driver, you can do this repair.  The first time my refrigerator stopped cooling, we were about to go on vacation in two days.  I had no idea what the problem was and knew I wasn't going to fix it before we left.  I called the appliance guy.  He walks in, opens the freezer door, closes it and says I know what the problem is and this what it is going to cost you.

So its that easy to diagnose.  If you have frost inside the freezer on the back, it is 90% chance that you need this part and a 10% chance you need to replace the timer.  The good advice that the appliance guy gave us was that you can manually defrost the freezer and get it working for another 4 days by putting all the food in coolers, opening the doors, turning off the power, and waiting 24 hours.  Then power up, put the food back, and wait for your part to arrive.  Once it arrives, replace the assembly, noting the original routing of the wiring.  It takes about a half hour, with most of the time spent loading and reloading the food into the freezer.