Leg shaking

Sounds like your body is warming up to the Aneros and progress is being made. You'll probably see significant improvements the more you ride. Good luck!

Would there be any reason why I am unable to get this to happen when I raise my back and the massager tail is not against the cushion @Mattp ?

I have no idea. But it is important to relax as much as possible. Lifting your butt may not be relaxing enough and causes the sensations to go away.

No idea too, sound like your quivering is not due to the pleasure.

Recently I found that my legs quiver too. But is due to the intense pleasure when my aneros hit right on the sweet spot. It happened while lying on my back with my gf held both of my legs closed and straight up in the air. I did even managed to get a few mini-o from that alone

Wow, so I'm laying on the couch with my Helix in. My legs are raised so that my feet are flat on the couch and I'm just relaxing. Not contracting or anything and I don't have any pillows to raise my lower back down there so the tail of my toy is in contact with the couch cushion. Anyway I've had it in for a little bit and I'm not feeling any pleasure in there although I can feel like a pressure a comfortable one. My legs have began shaking and quivering but that's really all that is happening. If I raise my but the shaking stops though. So what is this scenario exactly?

In my experience, it's your body reacting to the stimulation. I experienced that in my legs, my arms, my shoulders, my feet, ...basically all over...so don't be surprised if you do as well, or you may not! Just go with it!

TG