Time to remove this tree?
Your maple tree has a lot of dieback and dead wood in it. This may be in part due its yellowed leaves, a condition called iron chlorosis. These types of maples often struggle to take up iron from our alkaline soils. Since they need iron to make chlorophyll, your maple is not making enough chlorophyll, the green photosynthetically active pigment in leaves, so they look yellow. Lacking chlorophyll, the maple is not making enough foods for itself...so you get the dieback.
If this tree has any sentimental value, you may want to keep it and treat it for iron chlorosis. If not, it may be time to replace it with another type of tree that will grow well in our area's alkaline soils.
More info on iron chlorosis: http://www.ext.colostate.edu/mg/Gardennotes/223.html