Re: Help identifying and 'disassembling' a window - 1940s
I'd pry off the piece of stop molding (I think it's the left-hand one) and then the lower sash would be free to be un-hung from whatever counterbalance there is (if any). To remove the upper sash, the parting bead has to come out. I'm assuming that the removable one would be on the same side. If in fact the stop and parting beads on the right are molded-in, that would be a first for me. They have always been separate strips that are removable/replaceable. I can see no purpose in molding them into the jamb, as it takes so much more material and steps, to little if any advantage.
To get the parting bead out without breaking it, the upper sash must be lowered t the bottom. The sash is usually painted shut from both sides, and takes a long time with heat gun and the "window zipper" tool to free it. You may break it getting it out anyway, so be prepared to match it somehow. I usually plane my own from heart pine.
Since you already have triple-track storm windows, I wouldn't go to the trouble of adding insulated glass. I recommend (as I myself have done) to strip all the paint and glass, prime (oil primer) reglaze, paint the sash and frames before assembly (oil paint, again), and add some plastic "vee" weatherstripping (sides) and closed cell soft foam (top, bottom and check rails). and you'll appreciate the improvement. If solar gain is an issue, add window tint. It's about 90% as efficient as triple glazing, but at 10% of the cost if you DIY. The materials are very cheap, and it's just your labor, and every window you finish is money that doesn't leave your pocket.
Remove not the ancient landmark, which your fathers have set.