[Dickie]

I knew of their existence, but this is the first time I've had to deal with one of these "inside out" loudspeakers. (or should it be outside-in?). It's 6 1/2" dia. and only 1 3/8" deep.
I must preface this with the fact that it works OK. So anything I do to it needs to be non-invasive. I would like to clean off the rust and corrosion on the frame if possible and prevent it getting worse in the future. The magnet also has some surface corrosion but that is impossible to get at without dismantling things. I need to avoid getting the rust dust ending up glued to the magnet and worse places. I assume the front and rear metalwork sandwich the paper cone and it is all glued together. So dismantling is out of the question. I have thought of wire brushing it with a vacuum cleaner nozzle in close proximity, or maybe coating it with a layer of grease and scraping the rust off into a sticky mess.
Any ideas would be welcome!