Check the upper tank, pre and post motor filters for debris. Failure to properly maintain the filters could result in damage to the motor. A clogged hose may also cause the unit to sound different.
Please try the following to clear any possible clogs in the hoses:
- Upper hose - Detach the hose from the machine. 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, it may damage the hose. Drop a coin through the hose if it is detached from the unit as way to help determine if it is clogged, but remember it is very possible for a coin to pass through the hose even if a large clog exists.
- Lower hose - Remove the canister and then recline the unit. Look thru the hose for obstructions. Push a broomstick through lower hose to unclog. (The access plate can also be removed to gain better access to the lower hose).
If you continue to experience excessive noise, please have your machine inspected at a local BISSELL Authorized Service Center. You can locate a Service Center here.