Start with your vision of the triangle of vectors on paper. Point A - the aeroplane, is at the bottom (usually off the bottom), of the sliding scale (in the middle, where the zero speed would be).
The centre of the rotating circle can be either point B (the end of your TAS and Heading) or point C (the end of your track and groundspeed).
You choose which of these it wil be. When you draw the wind vector Up you are making the centre point C, when you draw the wind vector Down, you are making the circle centre point B.
The usual situation is you know your track (orientation line A-C) and your TAS (length vector A-B), but you don't know the length of A-C and you don't know the orientation of A-B.
Using the Wind Up method means your circle centre is point C of the vector triangle. The END of the wind vector (where the wind blows from) is point B of your vector triangle . You know the track you want to fly, so set it on the outer ring - the wind vector moves about, left or right. You know your TAS, so slide the speed scale up/down until your TAS is under the point B (start of the wind vector). You now have your vector triangle - point A (at the bottom of the scale), point B (the end of the TAS vector) and point C (the circle centre) being the Groundspeed vector. Now just read off your drift on the left/right degrees of the sliding scale, and your groundspeed under the centre circle. No fiddling required.
The fiddling comes with the Wind Down method because you are placing the end of your TAS vector in the centre (point B), from which you have to find out what drift will give you your desired track (point C). As you rotate the circle back and forwards, the drift changes, and so does the eventual track. You are trying to find the correct amount of drift that will produce the track you want to fly. That's what the fiddling is about - matching the drift on the scale, so that it will give the desired track from the selected heading. Finally, once the amount of drift gives the desired track, you can read your ground speed from under the end of the wind vector.
To visualise it all draw a (large-ish) vector diagram (random, TAS, random wind, random track), using the speed scale of the CRP your sepeed, then put you CRP over it - it then becomes more evident.
GB