CTX17BAZDRWH Hotpoint Refrigerator - Overview

To fully explain the symptoms on my refrigerator it would be nice to talk to a real live person. Most of the refr is still functional. It would not longer cool. Was told to shut it off for a day which really messes me up but did so. Then see how it works when brought on line again. Well it cooled very well for over a week. But not the temp has jumped up to 50 deg and will perhaps go higher. Initially the freezer worked fine but the food section was not working. I feel that what happened is that the bottom unit was not cooling because of a restriction which most likely is the unit iced up for whatever reasons. Well since it worked so well for over a week I thought my problems were gone. Not so. I should have known. I suspect some part of the defrost system is not working properly. Thus what is most suspect!!! Since loss of cooling causes food losses to me, I do not like this to continue. Pain in the butt if you know what I mean. Thus what part item do you think I should replace??