I have a vivi nova 2.8 ml. I went to take it apart to clean and bottom cap was on so tight I was unable to turn. I ended up having to use pliers to get it to turn. Now the threading head is slightly bent and difficult to screw on my battery. Just now I went to take it apart again to see if maybe that piece is replaceable and again it's so tight I can't turn it. I made sure last time to not put it so tight??? Is this a common problem with these and is that bottom piece replaceable or should I just get new tank? I did notice though that there is hardly anything to even grip to try to turn so should I stay away from these? I don't want to spend more money on something that will have same problem. I also have innokin iClear30 3ml. It has much larger base and is easy to take apart but I don't care for the look of it. Thanks for any tips and/or suggestions.