Late-seventies hardware age
That gap of ten years sounds small until you're standing in front of the hardware. A door installed in the late 1970s is more likely to have a single torsion spring on a header bracket that's seen forty-plus years of extreme desert heat cycling the steel, rather than the dual-spring setups and heavier galvanized track that became standard on houses built in the late '80s and '90s elsewhere in our coverage area.
