Replacement Windows Discussion Board Forum

Not looking to do the whole unit, just the pane of glass.... it goes on that inner frame that I can't seem to get out of there...

I have a basement window that the dog decided he wanted to paw at and shatter it. I was able to remove the screen and remove all the broken glass, but how the heck do I get frame out to get a new window in? I have pushed the sliders in and tried to move it each way... I have a strange feeling these ...