I asked this a while ago. I haven't tried it yet, but a forum member PM'd be these directions....
The instructions are in the manual and pretty basic except for the bit that explains the need for BOTH of the cresent-shaped spanners in the tool kit. You'll see once you start moving the lockout ring that you need to alternate using both of them in different positions on the ring to move it more than one click, or to move it back down if you need to.
Also, when you take out the coolant resevoir, note the position of the vent tube for reassembly.
Bend up a coat hanger so you can hang the resevoir upright and out of the way while you make the adjustment. If you don't, the tank is right in the way!
Try adjusting up to position 5 at first, and ride it a bit. I weigh 230, and 5 was a bit soft, but 6 was to much. The thing handles way more predictably now as you might imagine.
good luck.