Once I found that there were two recesses at 5 and 7 o'clock on the unit it took 30 seconds to remove the cover and 2-3 minutes to clean and regrease the unit. The recesses are next to the plastic cover to enable the cover to be prised off (not the two holes that are just in from the recesses these do nothing to help removing the cover).

All is now working except that my wiper rests one third over the windscreen, I think that the motor is out of sync? Any ideas.