How can you tell -- does the chassis look something like this? If so, it's the new version.
I've never had burnt taste with any of their cartos.....unless I vaped um dry.
The instructions say to fill with some drops & feed with the feeder----that insures you are getting juice at the bottom and it's evenly distributed. There is no need I know of to overfill from the top. I think most of us used more drops than the instructions state--but to each his own! For me, it just works better if you get some liquid from the feed even with a fresh carto. At least, that's what it seems like.
I'm guessing condom method not good for these---
And, a reminder -- don't leave out the big o ring.