This is from an active CN line (originally Grand Trunk) in my hometown of Guelph. I found a long dead tree branch and used it to spin off the insulator which was quite loose but the problem was that hanging broken insulator below it was still connected by a wire. I could only spin the insulator a little at a time and then push the broken one up and over the crossarm and repeat, it took me a good 20 minutes to unscrew it.