Try this to see if it helps. Turn proportional editing on. Go into edit mode and select a vertices. Press the "G" key and then immediately press the left mouse button . A dialog box should have opened at the bottom left of your screen. In the "Proportional Size" field enter 1.0. Now press the "G" key and you should see the circle of the proportional editing tool on screen. This should work if the problem was that the tool size setting was so high that scrolling didn't help.

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