how do or can you get a start from an old maple tree to plant somewhere else
To get an exact replica of the tree you would need to graft or bud a piece of the old tree onto a seedling rootstock of the same species. This is how commercial nurseries propagate thousands of the same variety of a tree. It's possible for hobbyists to do this, but it takes skill and some special tools to be effective. There are numerous nurseries in Oregon. Perhaps you could contract one of them to do it for you if you're not up to the task.