If you try and find a begining, for example.

Turn the top 5-10mm of the strut either anto clockwise or clockwise, but in the direction where as you find a point where it won't turn any further and start from there.

If your saying there on hard already, then the 'wall' wont be to far on turning.

Once you find that it is fully anti clockwise or clockwise, turn it the opposite direction, after about 360 degrees or 540 degrees, you should feel a click (feel not hear) this would be the stiffest setting i.e. No10.

Keep turning, feeling for clicks until you get to No1.

Sorted.