Clean the contacts in the mox mod with a pencil eraser, clean the 510 connection on the mod with a q-tip dipped in alcohol.
Tighten the screws in your atty, heat will loosen them sometimes. If that does not work, recoil the atty, and use a different set of batteries in the box mod.
If you fell your mod getting warm clean the threads of the mod too, if they get dirty it limits the threads from contacting each other, there by limiting the energy.