First, detach the brush from the main body and clean the connection area between the brush and the main body thoroughly. After taking these steps, reassemble and check if the issue persists. If the problem continues even after these measures, please proceed with A/S. When visiting in person, refer to the attached A/S center list and choose the nearest one. For postal A/S requests, send the package to the following address. Please include a brief description of the A/S request with your package. Zip code:04626. Address: Room 426, Main Building, 2, Toegye-ro 36-gil, Jung-gu, Seoul, Korea