Did Loonette from the Big Comfy Couch die?

The original "Loonette" is still alive. The original actress' name is Alyson Court. She was replaced in 2006 (one season) by Ramona Gilmour-Darling. I have googled it and they don't give a reason for her leaving, but her husband died in 2005, so you can see how her leaving might make sense. You can look her up on IMDB, where it lists a lot of voice work and some Canadian TV.