Most houses in Cerritos went up around 1974, which puts a lot of garage doors here right at the edge of their hardware's working life. A torsion spring rated for 10,000 cycles doesn't care what year it is - it cares how many times the door has gone up and down since it was wound. On a house built in the early '70s, that spring has likely seen close to fifty years of use, sometimes with no replacement at all if the door itself was never swapped.
The climate here doesn't do the damage that cold-weather towns see - no ice splitting seals, no freeze-thaw cracking slab anchors. It's mild, temperate air pulling steady humidity through the garage year-round. What that does instead is corrode springs and cables slowly, at the coil ends and cable nicks, without the dramatic snap that colder regions get. You get a spring that's been quietly losing tension for a decade rather than one that fails all at once - until the day it does.
Steel sectional doors from that era are also often original. If nobody's touched the door since the house was framed, the odds are decent that the rollers are the original steel ones, not nylon, and the drums and cables have never been resized for a heavier insulated retrofit panel someone may have swapped in later.