The median home in Libertyville was built around 1976, which puts most of the housing stock a decade or more past the oldest construction we see elsewhere in the territory. That matters for the hardware. A door from the mid-70s is almost always a steel sectional panel on a torsion spring, not the older one-piece slab doors with side-mount springs that show up on pre-1960s stock. Torsion setups from that era are more serviceable - parts are more standardized - but 48 years of cycling means original springs are well past their rated life, and the original rollers are usually the steel kind that's loud and starting to flat-spot. With 7,573 households in the area and median income at $162,270, well above the $113,125 figure for the wider service territory, we also see more two-car and oversized single doors with heavier insulated panels, which puts more load on an aging spring than the builder's original 1970s torsion bar was sized for. That combination - older spring, heavier door - is the most common failure we'd expect to find here.