Housing across this service area went up mostly between 1985 and 1991, and that build era matters here. Doors and track hardware installed in that window are past their expected service life - original rollers and track brackets from a house built in 1987 have had close to four decades of open-close cycles, and track alignment drifts as brackets loosen and studs settle over that time. Six named areas in the region share that same 1980s-90s housing stock, so this isn't a one-house quirk; it's a pattern tied to when the neighborhoods were built.
The climate here adds to it. This is a cold-moderate band, and temperature swings between hard freezes and warm afternoons make galvanized track and steel brackets expand and contract. Over enough cycles, mounting screws work loose in the jamb and brackets shift a fraction of an inch - enough for a roller to walk off the rail, especially on a door that's already carrying original hardware from the 1980s build wave.
Across the service area's roughly 8,775 households, with about 7,259 of those in owner-occupied houses, that's a large base of homes built in the same narrow window, aging the same way, on the same track hardware.