Previously, I removed the lower rear cardboard back of the unit and saw the crack in the defrost pan. It was probably damaged when unit was moved using appliance hand truck. I looked up the part number AP4319611 in the exploded view diagrams of the unit. The part was ordered and delivered in a few short days. Emptied the unit and removed all shelves/glass to avoid damage since the unit must be tilted enough to reach under and remove two 1/4 inch hex screws. Tilted to the right side (facing front) to also avoid compressor problems. Removed and replaced the pan and same screws. Confirm freezer drain tube is inserted into new pan. Return unit to upright position and reinstall shelves. Approximately 25 minutes with a helper.