I have two Carnivours, both have the standard "tin-roof" blades. Both had a little play in them (up & down in open position)when they first arrived, and I almost sent them back.
Anyway, as I played with them, they "wore-in" somehow.
Each actually tightened up with initial use (50-100 cycles).
Must be a characteristic of the "rolling lock" cam action.
Anyway, play with it for awhile and see if it get's better-mine did.
Bill