Rinse the pre-filter with cold running water or clean with Tineco rinse-free filter cleaning tool.
Reinstall the pre-filter correctly.
Reinstall the dustbin correctly.
Check the seal rings of motor air inlet/dustbin cover/mesh filter to make sure it's in good shape and well installed.
Contact Tineco Support Team.
A complete description of your problem or questions (with related photo or video) will enable us to support you more efficiently and effectively.