Extension spring versus torsion prevalence
That six-year gap matters more than it sounds. A lot of the doors we pull off in Frankenmuth are extension-spring setups from the late 70s and early 80s, not the older side-mounted torsion hardware we see in the oldest pockets of the service area. Extension springs fail differently than torsion springs: they stretch, fray, and sometimes let a cable jump the pulley instead of snapping clean.