The branches are laden with cones and seem healthy but the very top is dying and within two weeks has rapidly gone to brown and would like to know what intervention we need to do. We have had the tree for about 20 years and would hate to lose it.
Thank you for contacting Toronto Master Gardners.
There could be several issues with your tree but it is difficult to narrow down with out more information or a picture.
The obvious potential issue is the tree reacting to drought. Many trees are suffering this year. If you give your tree long slow watering, at least an hour, which allows the water to seep all the way down to the roots every few days it certainly will not hurt and may help.
Has there been any changes to the environment around the tree? Construction in your yard or a neighbours yard can affect your tree as its roots would spread out quite far past the drip line at this age.
I am attaching several articles from this site talking about different issues people have with Spruce trees. They also contain many links that you can follow for further information.
good luck