A house built in 1974 was framed before steel rollers, nylon idler bearings, and sealed ball-bearing hinges were standard. A lot of Cerritos garages still have the hardware that came with the house: single-piece torsion springs sized to old door weights, lift cables that have never been swapped, and steel tracks with the original mounting brackets. None of that is dangerous by itself, but fifty years of daily cycling wears it the same way it wears anywhere else - except here, because the stock is so uniform, we see the same failure pattern street after street rather than a mix of eras. The area's mild temperate climate means the hardware isn't fighting hard freezes or big humidity swings, so corrosion isn't usually the driver. Fatigue is. A spring rated for a certain number of cycles just reaches the end of its life, often without warning, after decades of use that never looked abnormal.