Fridge and freezer didn't cool enough

I diagnosed the problem via the internet. Diagrams helped a lot. Coils were frozen over. Thawed them out overnight. Manually advanced timer and the defrost heater was operable. The defrost timer wasn't "turning" on it's own. I turned the fridge back on while I awaited the part. It worked fine for the time I had to wait. (over two weeks since I had delayed ordering the part) New timer arrived as promised. Undid 4 hex head (1/4") screws. Unplugged 4 prong connection. Plugged in new timer and replaced the 4 screws. Frigde works great.