I found this info on the esmoking.net forum. I have not tried this yet but I see the gunk they are talking about.
You will run into a point in about a month of serious use with your Kr808d-1 when the inhale, or pull begins to get tough. Unlike the other ecigs where this is a atomizer issue - On the Kr808d-1 this is actually a battery issue. The rich, might just throw away the battery. The average, will learn to clean the battery to unclog it. I am sure, like many of you, you have never really had a clogged battery before. Well this is what you do :
1. Unscrew Cartamizer. Put it down away from your Battery.
2. Inspect the bottom, or the threaded part of the battery. Not the LED light end.
3. You should see "grime" in it. Look close, Around the ring inside. A sort of green dark grey grime. Also notice, grime on the 4 tiny holes around the outside of the thread. You may not see grime on them, but they are grimey.
4. Take a VERY thin, but stirdy wire and clean out both parts. MAKE SURE none of the grime gets into the battery hole in the middle. When I am missing a stirdy wire, I actually use hard bristles from a brush to clean it out. Be sure to do both as it is obvious both parts are what are causing the problem. Some even try cleaning inside the hole though that is risky.
5. Put it back together by grabbing the distanced cartamizer.
6. Take a drag. If it doesn't work well, clean again.
Happy Vaping!
Frank