We replace both cables as a pair even if only one has failed, because a cable that's frayed on one side almost always has a matching twin that's close behind - on a fifty-year-old drum system that's not an upsell, it's just how the wear pattern works. We check drum alignment and track spacing before we re-tension, since a cable replaced on a crooked track will fray again within months. On doors with the original torsion springs still in place, we inspect those at the same time, because a spring that's lost tension puts extra load on the new cable the moment we hand the door back. We test the door through a full open-close cycle under load before we call the job done. If the drums themselves are pitted or cracked from age, we'll say so - a new cable on a bad drum is a short-term fix, and we won't hand you that as if it's a long-term one.