Well I finally got a chance to spend some time with the freezer. After plugging it in for a few hours, this is what I observed:
The fan works. It runs all the time EXCEPT during the defrost cycle. It runs even when the door is open.
The defrost heater works. Went out to check on the freezer last night and didn't hear anything running, no compressor, no fan. I thought it was finally completely dead. I opened the door and it happened to be during a defrost cycle. The heater was hot and water was dripping off the evap coils.
The interior light works and shuts off when the door closes, as it should. The door gasket appears to be in good shape.
So, the timer, the heater, the fan...all work. I'm not sure what that leaves me? The thermostat or the compressor needs charged with new refrigerant?
There wasn't much frost on the evap coils but I took pics anyways. Here: