Alameda's own housing spans 1938 to 2005, but South San Francisco's median build year sits at 1963 - a few years ahead of the wider service area's 1965 midpoint, and squarely in the stretch where builders were still hanging steel doors on narrow steel tracks sized for those lighter panels. That matters because the rollers that came with those tracks were never meant to carry today's heavier insulated replacements some owners have since installed. When a heavier door rides on a track cut for a 1960s door, the rollers take the brunt of it: they wear unevenly, the stems bend, and the door starts binding at the same spot every time it opens. We see this pattern across the 1960s-70s stock that makes up most of this service area's 53 named communities, and South San Francisco's numbers put it right in that window. The fix usually isn't just swapping rollers one-for-one. If the track itself has worn to match the old roller wear pattern, new rollers in an old groove will bind again within a season. That's a judgment call we make at the door, not over the phone.