Thank you for your question, Jack.  Madrones are some of the most difficult plants to grow, and determining whether they are dying is somewhat of a puzzle.  Here is the list of known diseases:  https://pnwhandbooks.org/plantdisease/host-and-disease-descriptions?title=madrone. This article explains why their environment--above and below ground--is critical to their survival:  https://extension.oregonstate.edu/news/native-madrones-are-special-northwest

If, after reading this, you still believe there is something you should do differently, I suggest that you contact a certified arborist to examine it and provide recommendations.  You can find one in your area through this website:  https://www.treesaregood.org/findanarborist/findanarborist

Good luck!