It's easy to remove the old style head's chimney. The new style ones, with holes for the wicks seem harder to remove. I don't have the new ones, but from what I've read, it might be easier to remove the bottom grommet, take out the coil, and then insert an appropriate sized rod from the bottom to push the chimney out. Rather than pulling the chimney.
I don't have one, so I can't say for sure.