refrigerator stopped defrosting and iced up

In an effort to avoid buying a new refrigerator (sales people had said it sounded like a bad compressor and I likely needed a new one) or spending $$$ on a service call. I researched the problem online and determined that self-defrost failure was typically related to 3 parts; defrost timer, defrost thermastat, and/or evaporator heator. I first replaced the timer. However, the problem persisted, so I then replaced the thermastat and heater. The old thermsatat was visibly damaged as the cap had been distorted and was nearly pushed off the body of the part. Since installation of the new parts the fridge has functioned like new.
Total costs for the three parts was under $140.