Walk Behind Lawn Mowers

I recently purchased a Weed Eater mower with engine V550, model RV140, Type MR003G. After mowing for less than one hour I checked the air filter and found dirt and other particulate matter had gotten behind the filter. The problem, as I see it, is the air filter cover does not close tight enough at the bottom to squeeze the filter tight against the seal ridge. The paper cartridge is loose enough, at the bottom to allow dirt to go around it. I have it closed tight at the top but there is no mechanism to hold the bottom in close enough to seal the cartridge edges.
Thought you'd like to know.
Eric Ralle