I am new to vaping - I like cartomizers so I ordered about 30 of them - however I noticed that many of the cartomizers did not screw on the battery all the way. On my first and second battery - I just tightened the cartomizer all the way down - forced it - and ended up ruining the battery - because the centerpost in the cartomizer created depressions in the battery centerpost and no other cartomizers would work properly. I ended up ordering 3 more batteries - however now, I very lightly twist the cartomizer on until I get contact or a slight resistance - if it does not go on all the way down then I remove it and I take a steel dowel and push in (or down) the centerpost on the cartomizer, then it fits properly on the battery and vapes really well. I don't mess with the battery centerpost at all since cartomizers are not all identical (ie threads and centerpost height)...and I would rather preserve the integrity of the battery. I have not had to adjust a cartomizer centerpost out (or up) yet but I noticed that many people on-line do that as well. I also found a really great product at Radio Shack - it is called an electrical contact pen - and basically you can draw like a pen where ever you need to restore an electrical contact. It works on the threads and it restored the two ruined centerposts on first and second batterys.