Princeton's housing mostly went up around 2012, a decade newer than the 2002 median across the broader service area we work in, and that matters more than it sounds like it should. A newer build date means the original hardware - track, rollers, cable, hinges - has had less time in service, but it also means almost none of it has been touched or upgraded since the house was framed. Across the wider area, 52,521 of 77,529 households own their homes rather than rent, and owner-occupied houses are exactly the ones where nobody's replaced builder-grade rollers on a schedule; they get replaced when they fail. This region sits in a moderate heat band, not an extreme one, but summer expansion and contraction still works on steel track fasteners over years, and a track bracket that's a quarter-turn loose is often the difference between a door riding straight and a door that jumps the track on the next cold morning. With 6,809 households in Princeton, most sharing that same 2012-ish build year, the off-track calls we get here cluster around the same worn-roller, loose-bracket cause far more than they do in older neighborhoods with a wider mix of hardware ages.