Swapped the sprockets and cleaned up the engine as well as I could tonight, quite unsurprisingly the front sprocket area as well as the rear swingarm bottom guard were absolutely caked with old chain grease mud and other nasties.
Also took the rear axel carrier out for the bearing swap next weekend. Could someone with more mechanical skills than me explain one thing to me. The bearings in question are sealed on both sides and the spacer in between is just floating between them with nothing else to do than to be a spacer. WHY is there a grease nipple and the cavity in between is filled with grease?!