I have a MAYTAG plus MSD2356AEW and it suddenly is not cooling. What could be the problem and what do I do please?

SOURCE: I have a maytag plus model mzd2752gr and it's not cooling enough

To check the defrost circuit , unplug the refrig and inside the refrig section at the top about 2" in from each side in the back , there are "D" slots to put a finger in , and pull downward and foreward , to remove the control panel cover . Once removed , there is a 1/4" screw on each side holding the adjustment indicator panel on , 1 phillips screw behind both light bulbs , and 1 screw holding the complete panel to the rear wall . After removing these 5 screws , at the top right corner , with about 6-8 wires going to it , is the adaptive defrost board . Sometimes you can see the electronic board and on newer refrig's , a white box will be seen. Inside this box , is the adaptive defrost control . Disconnect the plug going to the board and on the right side of the PLUG , the far right wire is yellow , then another color , then white . Useing a small insulated wire with both ends stripped , insert one end into the yellow wire hole and the other into the white wire hole . This will bypass the adaptive board and send power directly thru the defrost bimetal ( thermostat ) AND heater to check if they are good .Plug the refrig back in . Now , wait about 3-5 min and look for a red glow at the bottom of the inside freezer panel , which will be the defrost heater or listen for sizzling which will be the frost melting and dripping onto the heater .If NO red glow , watch for a spark while removing the jumper wire you installed , from the plug . If a spark IS seen , then the heater was on and the heater AND bimetal are good . If you see the red glow , hear the sizzling , or see the spark , then the adaptive defrost board should be replaced . If no glow , sizzling or spark , then unplug the refrig and reinstall the refrig control section .
Remove the food in the freezer section enough so that the 2 screws holding the lower freezer panel on and the freezer panel , can be removed . Remove the panel . If the heater (black element at the bottom of the coils ) wires are visible , trace then to the top of the coils and disconnect . Use an ohm meter to determine if the element is good . If the element IS good , at the top of the coils , is a 1" cylinder with 2 wires , clipped onto the coils . This is the defrost thermostat ( bimetal ) . Replace this part if the element shows good . If the element shows bad , replace the element . NOTE 1 : sometimes the element and the bimetal come wired togather and the replacement part comes with a new heater and bimetal already wired togather . This would be the adviseable replacement part . However , each part can still be replaced individually . NOTE 2 : If looking at the bimetal and the top plastic " cap " looks cockeyed , replace the bimetal as moisture has gotten inside and disturbed its designed function .