I've had a fire

Best way to remove the smell is to get an activated charcoal cooker hood filter (cheap and available at any hardware store) and leave it scrunched up in the microwave for a couple of days with the door shut.(also a bowl of fresh cat litter works if it is the "fuller's earth" type without extra super-scented-power-globules etc..) If you are competent enough to take the cover off (make sure you know what you are doing or get a repair man to do it) then clean all round the extractor fan blades and where the air is ducted - there may be some soot that smells in this area. If there are no obvious holes in the interior as a result of the fire then if the machine seems to work normally there is probably no problem. the only way i know to remove this type of stain is with a (plastic scotchbrite type) scourer with some neat bleach (wear gloves) or some "cif/jif" type scouring cream. if a bit of effort with one of these doesn't do the job then you are probably best to live with the stains - make sure you clean all the cleaning products off properly before cooking in the machine again. If none of this works then try microwaving some sugar until it burns (watch it and stop it the moment it catches fire if it does). Sometimes this can remove burning smells even if this sounds very stupid it can work. last resort anyway. Hope this helps :)