Looks like the newest version of the Chimera does NOT have those flats machined on the heat break. Should be ok though - thread in the heat break loosely to the correct location, then tighten the nozzle against the heat break. You should be able to hold the heartbreak with your fingers to prevent rotation, if you need to use a tool for the Heat Break use a soft pair of pliers as to not scar the Stainless Steel. We will reach out to E3D and see if they can update instructions.
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