Is it the 'top' wiper ?
It is normal for the wipers on W116 , W126 and W107 cars which are of a similar design with unequal sweeps to park with one blade a little higher ( an inch or two ) than the other .
Like most cars , the wiper arms sit on splined spindles secured by a nut : they can be removed from the spindle and moved a spline or two either way but bear in mind this will affect the position at the other end of the sweep ( I know you wish to move your blade down , but for someone wishing to adjust the other way there is a danger of hitting the A pillar ) . To make this adjustment , just lift up the little hinged cap at the bottom of the wiper arm and you will see the securing nut ; with the nut off , the arm is likely to be 'stuck' to the splines and will need to be wiggled this way and that to free it off .
Also bear in mind that the park position is not always at the bottom of the sweep , and adjusting too far down can cause the wipers to go off the bottom edge of the windscreen which may damage , blades , paintwork or both .
If both wipers were not parking correctly , the adjustment is in the motor . I can't help with that never having 'done' one of these particular motors .
Hope this is of some help .