You'll want to stop
vaping and toss it out if it's not giving you much flavor anymore. There's a good chance the internal components might be burnt out as well. Last night I came across a thread that talked about "old style" 808 cartos literally burning out and it got me concerned about their safety. Not to alarm you but be cautious as to how you use them. Here are some general tips:
(1) Be sure to keep each carto freshly juiced by dropping
juice into it frequently (every 40 puffs or so, on average). So long as it's moist, there's a lesser chance of it burning out (figuratively and literally).
(2) If you can taste even a hint of it being burnt, toss it. It's not worth inhaling burnt stuff (analogs are good for this, however).
(3) If your cartos aren't meeting your own standards of preference, try a different brand. There are now several to choose from. I just ordered some Bloog-style Jumbo Drippers that supposedly last awhile, hold plenty of juice and do not "burn" easily. I believe they are horizontal coils which decrease the likelihood of burnout since the coil's on the bottom and not all along the length of the carto itself.
(4) After filling thoroughly, be sure the center is clear and that you can see light through it. If there's no airflow, there won't be much of a hit and hence a decrease in flavor.
(5) Use a higher resistance cartomizer if you're getting burn. The WOW! V4L cartos, for instance, are low resistance and heat up quickly so be careful how hard and frequently you vape.
(6) Try not to chain vape. This may be more of a personal preference but there's some science to it. The more frequently you're hitting it, the longer the wiring is staying hot and probably burning.
(7) Let your cartos "marinate" for awhile after you fill 'em. Let the juice absorb and let gravity and fluid dynamics settle it in.
I hope this helps. Now try ripping it apart with some tweezers or a paperclip and see if there's any damage. I did that to a couple of mine last night (even one that was still hitting well) and it was literally burnt in some parts. Waiting on the JDMF's as I hear they don't burn as easily (or possibly at all) if well-moistened.
Happy
vaping and be safe.