Okay, trying something a little bit wacky here while I wait for my brain to remember to see if I can get silica rope anywhere near me. (I also have an idea involving desoldering braid, and maybe a combination of the two -- or three if I get some PTBs involved, since I still have some lying around from older mod attempts.) I'm not quite yet ready to give up on the O-ring-type idea, so I've taken a new cartridge and am slathering the plastic cap with contact cement so that it comes up to and slightly over the lip of the center hole. Contact cement dries with slightly rubbery consistency so it may form an effective gasket around the needle and against the plate.
This may not be a good idea as the heat inside the atomizer might create rather unhealthy vapours (though probably not bad for the short duration I'll be testing this for), but this is just an experiment with what I have laying around; if it does work (being thinner than the silicone cap material and bonded to the plastic cap) then I can probably find a better sealant to try this with.
It's very slow drying stuff though so I won't know if it's effective 'til tomorrow.
This may not be a good idea as the heat inside the atomizer might create rather unhealthy vapours (though probably not bad for the short duration I'll be testing this for), but this is just an experiment with what I have laying around; if it does work (being thinner than the silicone cap material and bonded to the plastic cap) then I can probably find a better sealant to try this with.
It's very slow drying stuff though so I won't know if it's effective 'til tomorrow.