So the top pane is fixed and bottom slides up. the top is the one that broke and i went outside, knifed around the plastic trim and puddy and was able to just pull out the doublepane glass.
The glass was encased in a thin metal frame which fits right in the large overhung frame. You butt it up against the backing which is like 1/2" and then put the trim piece in front and putty it.
HOWEVER...i cant find a replacement glass anywhere..the guys at the shop dont understand what im needing and can only supply the BARE glass cut to the dimensions i need.
Can i use this or do i need one that is encased in the thin metal frame like I pulled out? see below to see how the glass sits in...