Please help, I've been using the Magma rda on my rDNA40. Everytime I use it, it works well in the beginning, but after I vape it for a while (1-2hours), it starts to work not very well (very little vapor production), then I always have to unscrew both screw and tighten it up again. It will show "New Coil Up", then I press (+) to accpet it. After that, it would work perfect like the beginning. It's very annoying because I have to unscrew and screw every 2hours, what should I do?? Thanks for helping, please forgive my bad English T_T