I got the grinder asetting cap off (2 screws) and the whole brass block unscrews with the top burr attached to it by 3 screws. Bottom burr is attached to the carreier with the centre shaft held on by a large nut. It was a bit yucky so I cleaned it, after screwing it back I think I have stuffed the alignment because it is now grinding too coarse.
I screwed the brass thingy as far as it goes, back it off a bit so that the screw holes line up and set the alignment mark to 0 which to me means Max closeness and then tested on 0,1,2,3 all progresively coarser so I think new burrs are in order unless there is an special alignment procdedure which escapes my very limited knowledge of grinders.
If someone can explain the coreect procedure it will be great