Installed in 1998 according to the newspapers date that was so thoughtfully rolled up and used for insulation. Its an aluminum single hung and the fixed upper sash seal has failed. I want to remove it but don’t want to damage the rest of the window as it’s not a size commonly available. The two panels of glass are spaced with aluminum stock and the entire sash appears to be mounted in a vinyl or other type plastic U channel. On the interior side the U channel is glued or otherwise solidly stuck to surrounding aluminum. On the exterior the vinyl channel can be pulled away exposing the edge of the glass assembly. I’ve no idea if the glass assembly is somehow affixed to the inside edge of the U channel. As shown in the picture I can bend down the exterior side of the U channel exposing the edge of the glass. But pushing om the inside doesn’t result in any movement of the glass in the area held down. The black substance exposed behind the vinyl is between the glass and aluminum spacer. I’ve searched the web and watched dozens of videos on window repair but nothing covers this situation. If I knew the glass was not affixed to the channel on the inside I could just cut away the exterior lip of the channel to get the glass out. Anyone know the likelihood of that or have other advice on getting this out? Thanks21D754DD-950C-4C10-B00F-3498F9CCE084.jpgE5D407FF-BBBA-4044-8301-09B6B8324BDF.jpgFD763542-C1BD-4878-B62B-C4C2D225BF08.jpg