Little tip, if you've got the Tobeco Marquis, on mine it was a huge pain in the ... to remove the bell cap from the deck piece and/or be able to twist it around to align the airholes. Those two o-rings at the bottom are overkill, so I removed the top o-ring, so now it's just one holding the bell cap on. It's still secure as heck, but I can at least take it off without a hernia now.
*edit* Oh, also, the o-ring around the drip tip on the Tobeco Marquis is notoriously wonky, it's too thick and can start to get really hard to settle it in place properly. If that's the case, you can try either a) lubing up the drip tip o-ring with juice, or b) what I eventually did, swap out the black o-ring the drip tip comes with, replacing it with whatever random o-ring you happen to have lying around that's just a bit thinner than the original. I've got one of those super tiny (like 2mm diameter) thick clear o-rings from my aromamizer stretched out to fit on the Marquis drip tip, and now it slips on and off like a glove, but still stays put otherwise.