Hopefully the carto has a defined center air channel - take the endcap off and see if you can see light through that air channel. Sometimes the air channel is or becomes a bit crooked blocking airflow and needs to be gently straightened by sticking a very straight thin paperclip into the mouth end of the central air channel and carefully out the threaded end hole and try to get the air channel to be straight enough so you can see light through it. Don't be rough or you can break or cross wires down there and ruin the carto.
Also - use manual batteries so sucking has less to do with getting vapor made.
In addition - an overfilled carto will not vape well. it will act like a flooded atomizer and not get warm enough.
And one more thing - juices with no VG at all make weak looking vapor and the vapor may disappear in your lungs. If you want more visible vapor then buy decent juices with some VG in them. I use 80PG/20VG in cartos. Thin enough to work well in anything, enough VG to smooth irritation and make a bit of nice vapor, but not so much that it would dull nicotine hit or flavor much. I also avoid all dark, cloudy or opaque juices - they often drop carto-clogging flavoring sediment.
And cartos have limited lives even with the best juices. I can get about 7-10 days use out of a carto.
Is there anything else you did between when the carto worked and then did not with the new juice?? Like did you attempt to clean or rinse the carto? Wet cartos do not work.