We make the adjustment with the screw marked in red.
Size 12 and 10
1. The more you unscrew from the pedal (reduce the slack) the higher the clutch will take (if you overdo it, it will slip or eventually give back the thrust bearing because it will be still supported but probably the pad of the clutch will say goodbye first)
2. The more you screw in the pedal (increase the slack) it will take lower. If you overdo it this way, the gears will not come in, it will grind and it will give back something in the gearbox because it will not disengage completely.
The stem should rest lightly on the pump, not loose, and have about 1 to 2 mm. idle stroke before it disengages the clutch.