Check filter. Clean if needed. The filter should be cleaned when it appears dirty. Simply remove filter, rinse thoroughly under warm running water until clear, then allow to thoroughly air dry. The drying is very important. Additional filter cleaning instructions are on page 13 of the manual.
Check the pleated exhaust (HEPA) filter. If dirty, cleaning is necessary. Instructions for removal and cleaning are on page 14 of the manual.
Check hose, wands, and power nozzle for blockages.
Hose: detach at both ends. The ends of the hose are the most common areas for a blockage. Check visually and clear as much as possible if present. If not visible, hold one end up and drop a coin in. Lift the end until the coin falls through. If it doesn't, there's a clog.
The easiest way to unclog a hose is to use an air pressure hose, or a canister vacuum that has an exhaust blower that the hose can be held too. If enough pressure, it will blow the dirt out. Make sure to put a plastic bag around the loose end to hold the dirt.
Visually check wands and power nozzle. The bend in the power nozzle connection is another common place for clogs. A wooden spoon handle, or similar blunt object, can be used to push the debris back toward the brush to clear a blockage here.
If none of these are the problem, contact a vacuum service center, preferably Hoover, for assistance.
Thank you for providing the brand and model info. It helps a lot.