I bought two used windows. They have some dents in the exterior frame that need to be straightened...

[IMG]http://i9.photobucket.com/albums/a100/oldmtnfart/mycamper003.jpg[
Has anyone done this before? I do not want to break the window glass, but I do not want to take them apart unless this is a last resort.
I was thinking about supporting the flange on a wood block and just using a hammer to tap the frame flat...

Steve