Click inside the wheel and then you can drag left/right or up/down. Unfortunately you can’t drag down very far, so this isn’t a very good option. However, if there are a number of options available for the tool and the adjustment wheel is off-center, you are unable to drag even half way across the screen, only allowing for moderate adjustments before having to enter numbers manually or dragging again and again. I think a better option here would be to click the wheel, activating the adjustment, brining up the numeric keypad, then you should be able to drag from anywhere on the screen, until clicking the adjustement wheel again, shutting off the adjustment on that wheel. This would allow you to drag completely across the screen, instead of only a possible maximum of 50%.