Like Ron hinted, drilling several holes on the arm where you want the window opened and using a small metal nail or pin, you can adjust the opening. Also while you have the screen out, make sure you have a couple of drain holes drilled along the bottom of the exterior frame to allow standing water to escape. There are no weep holes, like in the other windows, in the emergency window frame. See post #193 here for a picture of what I'm trying to describe.
http://www.escapeforum.org/forums/f8...k-3134-20.html
2nd picture