Maytag refrigerator model number MSD2641KEW
was not cooling very good.
Could tell the refrigerator had not been self defrosting as it should have been because of the frost build up in the freezer.
I check the defrost heater and defrost thermostat for continuity with my multimeter and found them to be ok.
To repair this refrigerator I replaced the Defrost Control Board, part # 67004704
I hope you find this helpful.
Here are the parts for the defrost system if you need to order them.
Defrost Control Board, part # 67004704
Defrost Heater Assembly, part # 67004188
Defrost Thermostat, part # 67004757