Ah grasshopper, when you get the cover off it will all become clear. .
The little bolt holds on a clamp that keeps the adjuster from turning by itself. .
Ideally, you just loosed the little bolt about 1/2 turn, turn the big slotted adjuster
and reclamp. . remember there is also an slack adjuster at the lever and where the cable goes into the
side cover. . the large slotted adjuster is the most 'coarse' adjustment.