Diagnosis
You have a two-stage filter system: a reusable foam filter and a pleated felt filter. Both require regular cleaning, but specific methods are critical.
How to Fix It
Remove the dust cup. The foam filter is in the front. The felt filter is behind it. Tap both filters over a trash can to remove loose dirt. Rinse the foam filter under lukewarm water until water runs clear. Gently squeeze, do not wring. Tap the felt filter to clean; do not rinse or get it wet. Let the foam filter air dry for 24 hours before reassembly.
If That Didn't Work
If suction remains poor after cleaning, the felt filter may be permanently clogged with fine dust. It is not washable. It must be replaced with part #161-0541. Order the official Bissell filter; off-brand filters often cause airflow problems.
Heads Up
Never run the vacuum without both filters installed. Never run it with a damp foam filter. Moisture will be pulled into the motor and cause corrosion or an electrical short.