Do you mean the bottom bottom portion? As in the donut-hole piece that secures the coil? Or do you mean the bottom piece that sits on the glass (the piece that screws into the chimney)? Cause that one was always a pain in the horse to unscrew for me too, those threads can get very tight very easily. If that's your deal too, it's probably not a sign of damage, just super tight threads. There aren't really issues with leaking there, so you can feel safe tightening it onto the glass a bit looser to make it easier to unscrew later.