Once we're on-site, the first job is matching the hardware to the house, not the catalog. On a door built close to 1973, that means checking spring size against actual door weight, not assuming the sticker on the spring (if it's even still readable) is correct. Cable routing and drum sizing on doors this age sometimes don't match current manufacturer specs, so we measure rather than guess. Most single-spring or cable jobs on a door this vintage run under two hours once we've confirmed the part fits; if we need a non-stock torsion spring sized for an older low-headroom track, that adds a wait we'll quote before we start, not after.