pretty sure the brass section was slip ring - there's a large gap where it used to be located. the many plastic shards are from the dislodged brass section grinding away at the plastic/melamine. the oil obviously speaks to other failings. my suggestion to glue in back in was not serious. time for a proper rebuild - i put it on the courier this morning.
not surprisingly, the bike died suddenly. but i am surprised I could restart the bike (sounded like on one cylinder) and ride it 3km to a mates garage.