Hello everyone and thanks in advance for your response. I am new to vapeing about 3½ months into it now, I have noticed all suppliers will not guarantee cartomisers only for DOA. Since I buy 4 or 5 boxes at a time I have not had any problems so far. My question, can cartomizers be checked before they are used? If so how? Because by the time I use a new one I won't know if it is a DOA or not. Thanks