1. First, check the Pre- and Post-Motor Filters for debris. Dirty filters can restrict airflow. The pre-motor filter may be hand-washed in cold water with mild detergent. Reinstall the filter when it is completely dry. If you don’t regularly maintain the filters, the buildup could damage the motor.
2. A clogged hose may also cause the unit to sound strange. Here’s how to unclog the hoses:
a) To clear the main upholstery hose:
First, detach the hose from the vacuum. Push a broomstick into the hose to push any obstruction to the curved end of the hose where it can be removed.
Note: A coat hanger is not recommended to clear a clog as it may damage the hose.
b) To clear the lower hose:
The lower hose can be found next to the right hand wheel. Remove the screw from the left side of the lower hose on back of the vacuum and straighten this section of hose by pulling it down or lay the vacuum out flat (you’ll need to push the handle release pedal twice) and roll it on its side with the lower hose towards the top side. Remove the hard plastic hose wand base (held up by a single screw) to expose the lower hose. Look through the hose for obstructions. Push a broomstick through lower hose to unclog. The access plate (the black plastic plate over the brush roll) can also be removed to gain better access to the lower hose. Note: A coat hanger is not recommended to clear a clog as it may damage the hose.
3. If your vacuum is still too 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.