I just repared my relatively new Hoover with a new motor. I am not an expert, but it sounds to me as if you have a seal / o-ring issue. I bought my motor from this website and am happy with its operation (hurricane Dennis flooded my den).
This link takes you to my model number, perhaps you can use some of these parts.
http://www.vacuumcleanershop.com/hvrmdlf7205900parts1.htm#8
B. Mobley
July 2005