Glendale's own housing stock spans 1979 to 2007 with a median build year of 2001. Avondale sits a notch newer than that citywide number, with its own median landing around 2002. That one-year shift doesn't sound like much until you're standing in the garage. A house built right around 2002 almost always shipped with a builder-grade steel torsion spring and a chain-drive opener from the same production run - parts made to a cost target, not a lifespan target.
The other factor is heat. This part of the valley sits in a severe heat band, and steel springs lose temper faster when they cycle through summer highs day after day for two decades straight. A spring rated for a certain number of cycles at moderate temperatures doesn't get that many cycles here before it fatigues and snaps - usually without warning, usually with the door half up.
So the fault pattern in Avondale isn't random. It's a narrow band of early-2000s hardware, aged out by heat, failing in the ways that generation of door was always going to fail. That's the case we're diagnosing for before the truck even leaves Glendale.