I've only been using a climber for a couple of years now, but have had enough adventures with them already to be very religious about wearing my harness. I've knocked the top half down to the platform simply by bumping it with my leg - simlilar to what someone else already mentioned. I've also had the platform slide down a wet hardwood tree about 12" while standing up to stretch. That sure gets the old ticker going. Now when I figure out where I want my climber to be, I cut into the tree with a limb saw at each of the four places where the teeth of my climber are supposed to bite. That has worked very well.