Actions: As they are a part of the circuit you should clean the threads with a clean dry cloth.

Tips: After vaping for extended periods of time, there may be a built up of residues on the screw thread which increase the contact resistance significantly. 

Clean them to make sure good electrical conductivity

1#  Cause: Faulty atomizer
2# Cause: Battery pin or atomizer pin is dirty
4# Cause: Battery pin is pushed down