Clogs that diminish suction can form from materials sticking to surfaces or wrapping around parts such as the floor brush bar or brush bristles. Additionally, an article of clothing, clump of hair or other large debris may cause a clog. Whether you have a canister or upright model vacuum, unclogging your vacuum cleaner simply requires that you access the area that has the clog and remove it.
Shake and pat the part over a trashcan to see if you can dislodge and dispose of the clog.