Racing Blue has the right answer. The wipers will take a set if left alone. They will be pointing up because of the way they sit every time after shutting them off. What you have to do is to bend the arm in the direction opposite of where they are pointing to make them neutral in their position, so they will flop to either side when in use. What you have is the wipers pointing up all the time and not flopping over to the other side to do the wiping. Either that or replace them with new more frequently, but at $40 / each from MB that is not the answer in my book.
Never ever found the need to twist the actual arm as in the metal arm . :surprise:
If your having wiper issues its normally :
1 you have not been cleaning your screen often
2 the windcreen being covered by some film residue
3 the windscreen wash fluid
4 you have cheap wiper blades
5 and yes even well known blades can cause issues as they are made to fit numerous hundreds of cars .
6 some sod has walked over your cars windscreen / arms and yes then they need adjusting .
7 you have used your wipers on a frosty / snowy day ( and that will ruin them )
8 fitted incorectly
9 wrong way up ( some older ones have spoilers on them )
10 newer ones are directional
Failing all that just use your car in the summer only :grin:
And when on offer the genuine blades you can pick them up for circa £24.00. >