Yes, I think I'm going to have to remove the window. Process of elimination over many rains and trail and error of covering areas have proven it to be the window. I've caulked the perimeter o the frame. Still leaking. A friend of mine with the same rig had the same issue with a window. He stopped it by putting a bead of caulk between the opening and fixed pane as he determined it was the hinge.
That why I'm asking if anyone else has realized a leak due to the hinge of the window.
I've ruled out just about everything most simply by the fact I get no water when the window is covered with plastic during rain.
It could be that many of these windows are leaking at the hinge. Owners just don't know it if the water is not migrating to a basement area like in my case. The unfortunate thing about that is you'll never know as the water will be in the walls.