After doing some research about the symptoms, this website had the manual to the unit, plus instructions on how to find where the parts were located in the unit and how to install the parts. These were step by step instructions. Problem has been fixed by replacing the defrost timer, the defrost heater and sensor in the freezer. The freezer had frost on the back wall and upon removing the back wall, found there was frost on the coils. This 10+ old GE unit is working like new again.