I'm inferring that you move up or down the Rampage/Exhausted line by one space per point you've adjusted your die roll, but I don't see that explained anywhere.
And you're moving on the little + and - squares, not just the large rectangles.
Your inference is correct on both counts, its one space per point and you move on the + and -
Depending on which version you have, it should say this in the "For Example" sections underneath Straining and Bottling. That's where it is in the current release, at least.