The job goes sideways when the pulley bracket itself has rusted through, not just the pulley. On a door this age, if the bracket at the back of the horizontal track is pitted or bent from decades of cable wear, a cable swap alone won't hold - we end up replacing the bracket too, which adds time once we're already up on the ladder.
It also goes sideways if someone's already tried a DIY fix with the wrong gauge cable or a mismatched pulley. We find spliced cables and hardware-store substitutes on these older doors more than we'd like, and those have to come out before we can trust the rest of the system. One limitation worth saying plainly: we're coming from Garner, 19 miles out, so this isn't a same-hour emergency stop - plan the call, and if the door is stuck in the down or up position in a way that's not dangerous, it can usually wait a day without getting worse.