Lately, I’ve noticed a cold draft coming in through my sash windows, and it’s making my heating work overtime. The windows look fine—no visible gaps—but I can definitely feel the air coming through, especially on windy days. I’m not sure if it’s an issue with the seals, the frame, or just normal wear and tear over time. I’d love to fix it without replacing the whole window, but I don’t know where to start. Has anyone here dealt with a similar issue? What’s the best way to seal up a draughty window?