you don't need to undo the cover.
pop off the rubber bung on there and you will see a 10mm nut and screw slot.
get a box spanner and slacken off the nut, with the screw driver through the box spanner lightly tighten,then back off 1/4 turn.
holding the driver tighten the nut so it don't move.
replace the bung
slack at the clutch lever = 5mm
drew