Refrigerator compartment is far too cold; everything freezing. Repair guy said problem was electronic control, so I replaced it. No change. Reading posts (e.g.,
this) on ApplianceJunk boards leads me to suspect that the problem is either that (a) the damper is broken or stuck in the open position, allowing cold air to flow endlessly from freezer into fridge compartment; or (b) thermistor in fridge compartment is disconnected or malfunctioning.
This parts diagram shows the thermistor as item #5, but I cannot determine the location.

And I'm not even sure where to look for the damper or what part # it is.
Advice on the diagnosis -- and the location of these parts -- would be appreciated.
Model
106.74209402