Originally Posted by datchew
If the filter is too long, this moves the cover outward which effectively reduces the pressure (or increases the opening) for the white o-ring.
The clamping force of the three screws will easily crush the filter. That cover will sit flat against the case no matter what. And the filter doesn't hold any pressure. The sealing thing is simply a function of the cover vs. the canister, which boils down to the case vs. the canister (once you take the cover gasket out of the picture).