one has come out - the other three have loosened and extended, but i cannot pull them out
i am assuming they were to stop the drum from moving or rotating however, as the drum can now rotate .. would it be ok to leave the three screws as they are - sticking out?
Why won't they come out excel ?, I would remove them in case they vibrated there way back in, in which case they would jam up your drum and most likely cause it some pretty serious damage.
If you don't have any grips pull on them with a pair of pliers while turning them or if you don't have any plies put something solid under them and prise them up while you are using the screwdriver or spanner.