Hi David, welcome to the A2oc
Double check this but I'm sure the only critical seals are made by the soft rubber flanges on the ends of the filter element.
Dirty air enters the filter housing and passes from the outer to inner face of the element. The (removable) bottom plate therefore does not need an airtight seal to the housing - it just needs to hold the filter firmly in position, as any air leakage will just enter the housing before going through the filter.
Hope this makes sense.
Cheers Spike