I dunno. I use EVODs all the time and I never have had to use pliers. You putting the hammerlock on them when you screw them on? I usually put just enough force to make contact with the battery contacts. If you have to screw down really hard, maybe you need to lower the contact pin in the EVOD. They are
threaded, so unscrew it a turn, and see if you need less force to make contact.
EDIT:
Tell me if this is confusing, I can use pictures or something to clarify....