The rear wiper on my mk2 was starting to get very slow in moving across the window. Disconnected the linkage from the motor and the motor moved freely, so that just left the shaft and housing to the wiper arm. I stripped down the shaft and housing, gave everything a clean and re-grease and the wiper is moving a lot more freely now. Remove the wiper arm, nut, thick washer, and thin washer Remove the trim on the inside of the boot lid, and then unbolt the nut that holds the linkage onto the motor, and two bolts holding the shaft housing to the boot lid. Here is the wiper shaft and housing removed. You can see the order of the washers also nut > thick washer > thin washer > boot frame > thin washer > shaft Just to note, at this point I was checking over how free the shaft moved inside the housing. The shaft only rotates over and back a half turn for the wiper to move across the rear window. This action was fairly tight and felt like it need freeing up. If I tried to do one full rotation of the shaft, it would bind up completely. There is a small c-clip holding the shaft in the housing. Pop this off with a small flat head screwdriver. It shouldn't give up much of a fight Once the c-clip is removed, a few taps of the hammer and comes the shaft. Take note of the spring washer at the base of the shaft The order of washers etc is as follows: shaft > spring washer > housing > o-ring > washer > c-clip The diameter of the housing is somewhere between 9.5 and 10mm. I ran a 9.5mm drill bit up and down the housing a few times to clean it out, rubbed down the shaft with a scotch pad, and re-greased everything. Put it all back together, check that it moves freely and then fit back to the car.
