Most of the housing across this service area went up between 1955 and 2005, with a heavy concentration in the 1960s and '70s across the 31 named neighborhoods we cover - Mission San Jose, Niles, Warm Springs, and the rest. Doors and openers installed during that build-out, or replaced once already since, are now old enough that torsion springs are past their rated cycle count and steel cable has started to fray from age rather than abuse.
The mild temperate climate here works against you in a quieter way than ice or heavy snow would. There's no hard freeze to crack a slab or seize a track, but the daily swing between a cool morning and a hot afternoon still makes steel expand and contract, and it makes the grease on an old spring coil dry out faster than owners expect. A door that's fine in March can bind in a July afternoon heat.
On houses from the earlier end of that 1955-2005 range, we still find original hardware nobody stocks new anymore - non-standard drums, older-style safety cables, torsion setups that don't match a modern parts kit off the shelf. That's a big part of why these calls come in as emergencies instead of scheduled tune-ups.