If Airflow was not an issue in the beginning but became an issue after continuous use, it is due to build up of residues near the chamber. It is often due to build up located in the interior air intake or the rotating stir base. Only those 2 areas come within direct contact with the vaporized substance so that is often the source of the problem. Fortunately, those areas are easily accessible and does not require disassembly. Please refer to procedures below for a quick tune up of your airflow.
Furthermore, timely general cleaning is also recommended - please see videos in the following section.