Some Hoover machines have two pumps, one is a circulation pump and the other pumps the water out of the machine. The one by the filter often has a blockage on a feeding pipe from drum to the pump eg coins being most common problem. Unscrew filter bearing in mind there could be water left in machine so put a towel down and unscrew slowly, letting a small amount of water out at a time, take the filter right out and shine a torch into the pump and check there is no obstructions holding the impeller, above the impeller the is a pipe which you need to check for blockages.
Paul ABC, October 2007