To remove the washer arms and service the washer hose or replace the washer nozzles you will firstly need to remove the plastic grill which lays at the top of the bonnet. This is made up of three sections, two end pieces and one main centre section.
The two end sections are secure with one T20 Torx screw and one plastic stud which is attached to the end piece.
The centre section is secured by 1 T20 Torx screws and 4 studs, again these are attached to the plastic and therefore care needs to be taken when releasing them or they will break off making it difficult to re-secure the plastic grill
This is best done on a warm day as the plastic grill has a number of plastic studs which secure it to the metal of the bonnet that will be hard and likely to break on a cold day.
The two end sections are removed first, remove the one T20 screw and release the plastic stud. T20 Torx bit is required to remove the screws.
I used a small socket which when pushed over the end of the stud projecting through the bonnet collapsed it allowing me to ease the plastic ends and grill away from the bonnet The round stud 1 is replaceable. The other clip 2 is not
Pay attention to the detail of the clips studs and screws making sure they are all removed and released before attempting to lift the grill, this clip is easily released with a small pair of pliers. Just lightly compress and apply gentle pressure on the clip or stud until the grill pushes away from the bonnet.
Having removed the left hand end piece the washer hose can be seen, Pay attention to the way this is secured to the plastic grill before removing for replacement.
Having removed both end pieces the centre section can now be released and laid back against the windscreen The washer nozzles and hose can now be accessed. It is worth noting that on this 2009 Classic model 'A' Class the washer nozzles are not heated as with my earlier W168 Elegance Model, it is therefore important to ensure that screen wash fluid is added to ensure the washer system does not freeze up, which could force the hose off the nozzle spigot or damage the hose. washer fluid /antifreeze would also protect the rear washer system which id difficult to access.
Note that the screws locate into speed nuts which are located on the plastic grill
Washer nozzle in housed position , I did not attempt to remove, it appears to have small clips that retain it in position.
If the reason for removing the grill was to remove the wiper arms remember to mark to exact position of the arm and wiper blade on the screen before removing this will enable you to replace the existing or new arms in precisely the same position as when removed .This action will in turn prevent the blades clashing when the wipers are used.
To access the securing nut , remove the plastic cap this can only be done using some form of grips but do not damage the cap as it needs to be replaced.
Having removed the nut, wiggle the arm on its spindle and it will come off the spline. When replacing do not over tighten.