Getting to the wiper assembly is a “fiddly” job — unless you remove the bonnett, the battery, the glovebox and the scuttle vent. THen you can get to ever thing with “relative” ease. I rebuilt my wipers with parts from Nauss automotive in the U.S. Adjusting the brass tube and the length of the wiper arms is critical. The 4 degree bends in the arms allow for a very precise adjustment to make the unit move smoothly.
You will never get this done without removing the battery/scuttle/glovebox to allow access.
Thanks for a great forum!