Help: Magnolia Tree

Tree is slowly deteriorating, especially in the last 2 years.

Several “wounds” where it’s not healed from pruning. Leaves are yellowing, Plant Parent says that’s from underwatering, but the ground is almost saturated, we’re in Cumbria and it’s not dry.

Don’t want to loose it, because the flowers are spectacular. Although it’s not flowered well I. The last two years.