yup its a bit of a trick, push them in all the way and then tighten them to the extent that the rings are snug but not crushed, you don't want to squeeze those boots to hard anyways you can split, crack or let some air in past the filter, just nice and snug. I have a friend of mine (and i might try this) who puts a little bit, like a smear of shoe goo (bought at any hardware store) around the inside of the filter opening then seats it on the carb snugs it up, waits for it to dry and done, water tight, won't hurt any rubber, and when you remove it it peels off sort of like when you put white glue on your hands.
Peronally i think shoe goo is way up there with gopher tape.
