I find that it really depends on the flavor... Flavors like Cinnamon, mint etc seem impossible to get out completely. Best best is to overwhelm the new carto refill with a strong flavor.
I was able to recycle V4L cartomizers with some success...belle triste has a great video on how to boil and clean cartos...
If you are going to empty out a menthol and replace it with a better tasting menthol... or cinnamon or apple or any "same" flavor, you can probably just blow the heck out of it, spin it etc and refill it.
I did get a leaford lanyard... but before it arrived I made one with an id card holder or sportscard holder and a piece of string... spun it etc...
Have you tried the classified
thread to see if you can swap with some one? Good Luck!
Great Idea...
One man's waste is another man's treasure.