I also use a Trouble Light balanced inside the case and leave it on for days. The end of the light with the cord keeps the lid slightly open leaving space. I make sure nothing is touching the shield as that does get warm or even hot. I read this somewhere a long time ago and has worked very well for me. Supposedly the heat from the light kills whatever is causing the odor. I am very careful in the placement and have never scorched anything. I imagine the low light bulb just keeps a constant warm temperature. I just used it in another Featherweight case and it worked pretty good. For the larger cases it's easier.
Good Luck,
Lisa