Been there buddy, except my version of that story is I spent a whole night cussing at a bad ground only to find out my tip was just loose the entire time. Plumber's tape on the threads is a new one to me though, and I'm kinda mad I never thought of it. The tape is PTFE so it should take the heat fine, that stuff is rated way higher than 700, but I would keep an eye on it since it can get gummy if the joint area gets really hot. Worst case you just rewrap it every few weeks, which beats buying a new iron. How long does one wrap usually last you before it starts acting up again?

Well damn, positive rake saved my 17-4 job too, chatter just vanished.

Coal smoke probably left way more soot than creosote compared to seasoned wood.