Any chance she was starting to be broody? They'll pull out their own feathers to make nesting material. Being broody is very hard on a bird, especially if you're in a warm area of the country--maybe that plus the lung issue? The birds I've processed, the description of the heart size sounded normal to me.To start out we found an area on her chest that did not have feathers growing. The only way to see the bald spot was by moving the other feathers out of the way.