Old thread, but I recently did this myself, and took pictures
And I did this without removing the metal plate on the wiper motor.
Remove the plastic cover over the motor and linkage:
http://i243.photobucket.com/albums/ff282/addey27/alfa%20vindusvisker/2.jpg
Remove the wipers (I found it was easier when pressing the joint down like this):
http://i243.photobucket.com/albums/f...usvisker/3.jpg
I also didn't bother removing the entire plastic lid, just slid a piece of wood underneath to hold it up.
http://i243.photobucket.com/albums/f...usvisker/5.jpg
Untighten this bolt to disassemble the linkage from the motor:
http://i243.photobucket.com/albums/f...usvisker/6.jpg
The bolts marked in red fasten the wiper motor. Unscrew these. The one marked in green holds the metal lid in place, remove this as well.
http://i243.photobucket.com/albums/f...usvisker/7.jpg
Next is to remove the entire linkage, one bolt here:
http://i243.photobucket.com/albums/f...usvisker/8.jpg
And one bolt here:
http://i243.photobucket.com/albums/f...usvisker/9.jpg
The electrical connectors to the motor are a bit tricky to get off:
http://i243.photobucket.com/albums/f...svisker/10.jpg
I found it easiest to do with a small flat-head screwdriver, just press the spring down while pulling on the plug:
http://i243.photobucket.com/albums/f...svisker/11.jpg
Now, the entire motor is loose. Remove the plastic lid by prying all the tabs marked:
http://i243.photobucket.com/albums/f...svisker/12.jpg
As you can see, lots of grease:
http://i243.photobucket.com/albums/f...svisker/13.jpg
I actually just removed the motor cover, and turned the motor by hand to turn the metal disk. I used Q-tips and paper, just pressed them into the slots while turning the motor. No need to remove the ribbeted plate at all! And nice and clean afterwards:
http://i243.photobucket.com/albums/f...svisker/14.jpg
Assembly is in reverse order. Just take care about one thing: Before mounting the linkage on the motor (picture 7 above), switch on the wipers and let them run a cycle so that you know it's in it's resting position (if you're unsure if it was when you started...). Then, be very sure that the link mounted on the motor is placed so that there is no bend in the link (see picture 6). Otherwise, the wipers will try to move off down below the windscreen...