The gutter runs over, only at the downspout. so the downspout must be clogged. I put a garden hose up the downspout but the second floor of the house overhangs the first floor by 18" so there is a double turn in the downspout, and I could only get about 10 feet of hose in.
Still I decided to see what the water would, and water came spraying out from many places at the double turn. It shows that the connections are only "waterproof" when the water is going down, not up.
Any idea how to push the hose beyond these two 100 or 110^ bends? I put a sweeper nozzle on it just to help it around the corners, but it didn't help.