My best guess in order of where I would start first, however your "clucking noise" has me perplexed sounds like a worn compressor. How cold is the freezer exactly in measurement of temp...? , cold is not an answer btw.
Damper Control Assembly
Thermistor
Evaporator Fan
Defrost Timer
defrost thermostat
Evaporator Coils
I have my 609 cert... I thought about getting my 608 III. I always liked working refrigeration.