Started vaping over the summer, started out with a V2 set up. hated the cotton fiiled cartos and tried the Pheonix bottom coil cartos. they worked great at first but man it didn"t take long for them to start leaking. out of the five i bought about a month ago only two won"t leak all the juice out right after i fill them and the the other two leak when they start to get empty. is this common for these and should i look for something else to use?