I unplugged the fridge and took all the food and shelving out of the freezer and then proceeded to take off the bottom sliding drawer rack on both sides off (4 Phillips head screws). Then took off the light bulb cover and then the light bulb. Then the back wall that covers the coils and tubes that the refrigerant runs through ( 2 screws with hex head). After sliding out the back wall I could see that the entire coil area was frosted and iced up. I took a blow dryer and melted all of it over about 40 mins and cleaned up the excess water mess it left in front of and behind the fridge. I immediately looked at the bottom of the coils to where the heater bulb is and could tell that the bulb was burned out and fried on one side of the connector piece the bulb assembly. I then proceeded to put it all back together and plug it back in so as to keep it functioning while I awaited the parts I ordered. The fridge and freezer will function and cool correctly for a week minimum while the coils frost over again slowly. I ordered the 2 thermistors and the defroster limiter as well as the defroster heater assembly just to ensure that all components that run the defrosting were fully functioning. About 76 dollars including shipping. Once the parts were in I went through the previous mentioned steps (MAKE SURE YOU UNPLUG AS BEFORE) and once the coiled area is defrosted I first took out the defrost heater assembly. There is a aluminum bracket that covers access and it is 2 phillip head screws. The heater assembly disconnects on both sides where the wires run down the freezer into the tan porcelain ends of the heater bulb assembly. Reinstall the new one in the same way and screw bracket and assembly back on. The defroster limitor is at the top of the coils sitting under the light bulb area. Just carefully pull off the coil pipe and snip and strip the 2 wire with a pair of wire snips/strippers. My advice is to watch the instructional videos on the website on replacing the defroster limiter and the thermistors. You will need the type of wire connectors they show on the videos that can be crimped and can easily find them from a local auto store or home repair store or a hardware store. PAY ATTENTION HERE, the wires for thermistors and defroster limiter have no positive or negative side so it makes NO difference which of the 2 wires connects to each other. I verified this with customer service and thus my unit has worked perfectly since the repair. FYI the first freezer thermistor is near the defroster limiter and the second is located at the bottom left corner tucked away. Both can be seen on instructional videos. Hope this saves someone a lot of time and irritation.