Hello, this is my first post. Koko is a 20 year old, Yellow Naped Amazon. Lately I have noticed that his beak is always slightly open but it looks like he's closing it, so a slight gap would be a more accurate description. He did have a change in diet for two months and is now back on his regular diet. he seems pretty normal other than that. Does anyone have any ideas of what the problem is, if there is one. Any feedback is appreciated. Thank you!