South San Francisco's housing mostly went up around 1963, right in the middle of the 1938-2005 build window we see across this whole stretch of the bay, where the median lands at 1965. That era means steel track, galvanized rollers, and extension-spring setups that were standard then and are still hanging on original hardware in a lot of garages here. Track brackets from that period were fastened with lag screws into framing that's shifted a little over sixty years, and that's usually where an off-track door starts: not a dramatic snap, but a slow lean in the vertical track that lets a roller walk out of the channel on the next close. We're not dealing with coastal fog damage or freeze-thaw cracking here - the climate band for this whole service area is mild temperate, so track failure is almost always mechanical wear or a bent rail from something hitting the door, not weather. That narrows down what we check first when we get a call from this side of the bay.