One of my neighbors had a similar problem, and after watching the technicians work I realized they use much more than a simple vacuum. They had a powerful vacuum system connected to the duct, along with long flexible rotary brushes that reached all the way through the vent line. They also used extension rods so they could clean every section without taking everything apart. The technician explained that the equipment is designed to remove packed lint instead of just pushing it farther into the duct. The whole visit was surprisingly quick, and afterward the dryer finished loads much faster. Seeing the process in person convinced me that the professional tools are made for both efficiency and safety, especially if the duct hasn't been cleaned for several years.