You have the squished 0 version? I don't think there's anything to dislodge in the D's. Maybe I've just been lucky, but I can't see anything. They're designed differently from the round carts (obviously, but internally as well).
I have both the 0 version which I'm not sure which part you'd be referring to as 'squished' (ok, I think you just mean that it's a O squished to more like a 0 shape flat on the sides where the air channels are - well, like any other 510 cart

. The actual whistle tip of the 0 version is wider vertically by over a third but less than half, than the D version. And I prefer the 0 version - I like the feel and it's a bit more substantial for holding in your teeth (not that you can't do it with the other one.
The D version I have is again, narrower vertically and the cartride is D shaped with the air channel that is cut just above the point where the atomizer casing would .... against the edge of the cartridge/mouthpiece, Iow, it isn't one that you describe where the air channel is at the same level as the top of the cart.
Like all 510 carts there is a 'floor of the cartridge itself' that holds the filler and keeps the filler from going completely to the bottom of the mouthpiece - it is also what keeps
juice from going straight through the mouthpiece hole, where you draw. I think what I did when I pulled the filler to clean it, that because the bottom of the filler material was glued to that plate that I dislodged that plate from where it is wedged in, and as a result, that opened up a 'path' for juice to go to the mouth piece hole. I tried to find the original spot of the floor plate but it wouldn't stay there. Had they not glued the filler material to that plate, I wouldn't have had the problem.
I've just taken them 'out of rotation' and am using the ones I got from dietsmokes and ecigexpress. The D ones from eastmall are in a larger box with blue writing - 'mini cigarette' atomized cartridge - which it is not, so I'm guessing they just grabbed those boxes for the flat tips.