GE French Door Fridge GFE28GMKES Freezer Not Freezing Properly

[PhillyUnion52]

Noticed this problem a few weeks ago, the freezer was not cold enough, food was starting to get soft.  Took apart the freezer to find the evaporate coils frozen.  Melted everything, found the evaporate drain tube clogged and put everything back together.  The issue presented again in about 3 to 4 weeks, so I'm guessing I have a defrost issue based on my research. Some more info:

• Freezer defrost heater tested at 32 ohms, which I believe means it is okay
• Tested the freezer thermostat at room temperature at then at 150 degrees, everything tested fine.
• Evaporator fan does run at certain points. I don't think that is the issue.
• In Service Mode I get an error code of 0010, not sure if this related to the issue.

Based on my limited knowledge, the freezer thermistor could be an issue? Am I on the right track here?  Any other insights on next steps. 

[Budget Appliance Repair]

24 minutes ago, PhillyUnion52 said:

Based on my limited knowledge, the freezer thermistor could be an issue?

Not the actual freezer temp sensor thermistor but the "Freezer Evaporator Thermistor", the one attached to the evaporator coil is the one that controls defrost and is under the harshest conditions going form low to high temps.