On top of the rear axle is a slotted vent plate, underneath you find a rod sticking up under 45 degrees, if you release the counternut you can adjust the parking band brake.
It might be easier to undo the M8 bolts of the cab floor and move it out of the way by stuffing a firewood log between the cab floor and 3pt hitch cover so you can work freely. Do not forget to take of the 3pt, remote hydraulics and P-M-D lever knobs off before you attempt...