I'm so sorry, and I hope they don't tell you it's uncurable… or inoperable… though this would seem to be a difficult procedure. I'm so sorry, and I hope Marigold continues to stay strong and happy.
I'm glad in a sense to see that you are such a compassionate owner. I've known a number of people who simply watch as their birds nibble their toes away, break their legs or wings, and become chronic egg layers in tiny cages. However, your birds always look so happy and vigorous, even when there in poorer health!
Congrats on being a great owner!