What PG/VG of juice are you using? Thick juices do not work well in cartos. I find 20% VG in a juice is the most VG I can have to get the best continued performance out of a carto.
And what is your problem with cartos? Are you singeing them? Not getting good reuse out of them? I can get 1-2 weeks use out of a Boge if I use a thin fairly clear juice (a juice with no sediment in the flavoring)
This is how I use them:
How I fill
Pop out the soft cap with an unbent paperclip in the mouth hole, very careful not to catch stuffing or the wire loop.
Shake and open the eliquid
Hold a bit of tissue on the threaded end hole, tilt the carto, and add 18+ drops per ml of capacity into the stuffing (Boges are about 1ml)
Clean up the threaded end, tilt open end down into tissue, puff into threaded end to clear air channel (Boges have a defined center air channel and I want to see light through that)
Sop up any loose juice above the stuffing
Cap and let it settle - I lay it on different sides for 15-20 minutes to make sure every bit of stuffing gets damp so I won't singe the carto. if you use thicker juice than me (I use 30% Vg or less, I prefer 20%) then you may need to wait much longer.
While vaping, if the vapor gets a bit light or a bit dry or the carto is getting hotter than normal, I take the carto off the battery and add eliquid. I sometimes use a plastic or delrin drip tip as a mouthpiece on Boge cartos (not to drip into since the juice would head for the central air channel)