Let’s talk about repairing broken glass in an aluminum frame single hung window. If it’s the lower sash pane that is broken, it must be removed from the inside. You are going to have one of three different mechanisms that hold the lower sash up when you slide it open. If you can’t see any mechanisms on the sides, then you have a block and tackle system consisting of a string and spring assembly. Find the thin metal clips in the side jambs just above the sash. Pull the bottom of the clip out using a screwdriver or your fingernail. Do that on both sides. Then remove any rubber stops at the very top of the window. Raise the window as high as it will go. The block and tackle assemblies will get snagged in the metal clips, allowing you to remove the window sash. You would replace the glass using the same method described in our article about sliding window repairs. Once you have the new glass installed, install the window panel in the reverse order that you removed it. Close the window and push the metal clips back. Install the rubber stops at the top.
If you have a mechanism across the top of the window with a string coming down each side and screwed into...