1. Check the upper tank and the pre and post motor filters for debris. The pre-motor filter is found in a drawer right below the dirt container. The post-motor filter is on the back of the vacuum below the hose. Failure to properly maintain the filters could result in damage to the motor. Please note: The Lift-Off® Multi Cyclonic series do not have upper tank filters. Check the upper cyclone for debris. The cap is removable for cleaning.
2. Check the hoses for clogs.
Please note: a coat hanger is not recommended for clearing clogs as it may damage the hose.
To clear the main hose:
Detach the hose from the machine by unscrewing counterclockwise. Push a broomstick into the hose to push any obstruction to the end of the hose where it can be removed.
To clear the lower hose:
The lower hose can be seen after removing the Lift-Off® Canister. It’s to the right of the detent pedal. Recline the unit and look through the hose for obstructions.
Push a broomstick through lower hose to unclog. The access plate (black plastic frame over the brush roll) can also be removed to gain better access to the lower hose.
3. Make sure the brush isn’t making excessive noise. Unplug the machine and unscrew the black plastic access plate that covers the brush. Remove the brush and belt. Recline the vacuum (the handle has to be reclined in order for the brush motor to work), plug it back in, turn it on, and see if the noise goes away. If the noise goes away, you’ll need to order a new brush, which you can do by clicking here: http://www.bissell.com/15-brush-roll-for-lift-off-upright-pet-vacuums-2032085
4. If the above step doesn’t work and the vacuum is still loud, please take it to a technician. You can find your nearest BISSELL® Authorized Service Center by clicking http://www.bissell.com/support/product-support/service-centers/ or by calling 1-800-237-7691, available 24 hours a day.