There are a couple of approaches. Most likely, the camera has been in a damp environment and hasn't seen light for some time. I've use a couple of options. First is line a file box (typical of OfficeMax/Depot) with a heavy black garbage bag. Arrange all items in the bottom of the box. Purchase some of these
chlorine dioxide packs and place one in the corner of the box. Seal the bag up with a twist tie and leave for 2-3 weeks. You can include lens cases and anything else that has been affected.
After three weeks, ventilate the bag outdoors allowing everything to return to normal air. Check the status of the odor. If it's still not completely gone, using the same technique, however this time replace the little bag of ClO2 with a dish of mint scented rubbing alcohol. Without spilling the dish, again seal up the bag, but this time add a few "breathing holes". The alcohol will 'scent' the contents, but evaporate. Once evaporated (1 pint should take about a week or longer), your equipment should pass the sniff test. Good luck.