Why is my footage shaky or why can't I do a full Roll360?

You need to be sure to balance your pan axis. This is what's causing your shaky footage. The motors on the Ronin-S are strong but they won't be able to power through if the system isn't balanced. This is very apparent when you try to perform a Roll360 and the motor seems to give up. Usually you'll get all the axes balanced and forget the pan axis as the entire gimbal is sitting on a flat surface. The pan axis will appear balanced because the gimbal isn't tilting or panning one particular way.

This is a typical setup a lot of users will have on the Ronin-S. This is a Sony A7RIII with a Sony G-Master 24-70mm lens. With this weight, you can see how far back the pan arm adjustment needs to be to achieve a perfect balance.

Now what we're seeing are users balancing their cameras and forgetting to adjust the pan axis as seen in the image here. The gimbal may appear balanced because it's not swinging one way or the other but it's not. If you tilt the gimbal forward or backward or put it into flashlight mode, it will be extremely biased towards the rear of the camera. Just by looking at photos of setups, we can tell the gimbal isn't balanced because of how far forward the pan axis arm sits.