@Birdyman88 Firstly, thank you! Secondly, let me assure you that I never thought of the Rope Wrench as life support--I've read plenty, plenty, plenty to know that the hitch is the thing. However, what I was trying to say was that I was pulling down on the hitch, the way I saw it in the video--and nothing was moving.
I'd better add a "thirdly" in here to say that, before I ever hooked into a saddle ring, I had hung the equipment on a rope suspended from the ceiling and experimented with the setup. I could see that as the pulley went up it released the hitch and pushed it up with it, and that the tether made the Wrench go into "neutral" (as the company names it) and it went up too, and that when I stopped and pulled down on the pulley, simulating my weight, the hitch locked. What I was saying was that for the longest time I could not pull the hitch down.
I went back to the photos and descriptions to check that I had everything hooked up the same way. Check. I thought I was pulling down "pretty hard" on the hitch, but nothing was moving, and I had no experience with "how much" friction the Wrench was going to supply, so I had begun to wonder if I had, perhaps too big a diameter hitch cord, or too many turns in the hitch, or if, say, I needed to put hold my hand a certain way? Finally, I discovered that I wasn't pulling down hard enough on the hitch to get it moving. Again, not something that can be learned from pictures. But the fact that it DID release in the experiment encouraged me that the setup was working the way it was supposed to and I moved on to trying myself in it from a low branch.
The other confusion did in fact arise from me not having a saddle like the ones in the pictures, and trying to use a sling as a chest harness as some do, but mostly from trying to jump straight to a bridge setup without having even been suspended once. By the time I'd practiced a few hours with things in adjustment, I did have a much, much better feel for how it was going to work.
The motivation for SRT for me is simple: I want to step up the rope. Today I learned that I can do it and it's not going to leave me exhausted. Of course getting into the tree is just the beginning. I'll still have to learn how to move about, let alone how to work.