I say rip it apart and figure it out. what I have found about english engineering is that it's overly complicated but pretty simple for maintenance at the same time. keep your parts organized. you shouldn't have to get into the electrical too much to change the axle. where did you find your diagram? I have a dynohub on a loaner bike that, once it comes home, will get rebuilt and I'd love to have something to look at.
edit: if it's already screwed up what do you have to lose?