New Eureka 5893 BVZ looses suction

I am trying to help my daughter out. She bought a new Eureka Boss 4D vacuum cleaner at Walmart. It is model 5893 BVZ. After a few weeks the suction went down to almost nothing. She had lost the receipt. Walmart was kind enough to swap her for their floor model. After two weeks the same thing happened. I have cleaned all the filters and checked for clogs. What I found is a vacuum leak where the dust cup filter cover meets the body of the vacuum cleaner. If I put masking tape over this junction all around the cover full suction is restored at the end of the hose. The cover is not broken or bent. It almost seems like there should be a gasket on this cover. I am trying to get help from Eureka but I can tell from their answer they don't understand what I am saying. I tried sending pictures but their server keeps telling me the message is too large and blocks it. Any ideas or suggestions? Does someone have this vacuum? Does yours have a gasket on the dust cup filter cover? Thank you.