The failure mode is ordinary. The phone rings during the weeks before the first cold snap, when a season of fires is still in the flue, nobody answers, and the first fire of the season goes into a flue nobody swept.
Knox answers and writes stove or fireplace, and about how many cords burned before talking about a clock time. The Brush passes turns those counts into brush passes so the company sees a size, not a vague "can you come look."
Then one company is offered the note. A local sweep brushes and shoots the flue. Knox does not rebuild the crown. If the window cannot be met, the caller hears the next real opening, not a promise that keeps the board pretty.
The note is the product. A callback that skips stove or fireplace, and about how many cords burned creates the second angry call.
