Put some deodorant type soap in the case, like Irish Spring or Safeguard. It was recommended by "Featherweight Fred" from Texas. He specializes in FWs. He recommended this to me two years ago, and it works. Just be sure to leave it in the box with the end cut off, so it doesn't touch anything in the case. Sunshine helps a whole lot and use the soap when you can't have it out in the sun. It saved my original case. I was going to not use it anymore until I tried this way of deodorizing it. The old hide glue in the old cases molds badly and unless you gut them and redo the fabric, they always tend to do that. Just the way they are and we have to work around it. This method is not hazardous though. Happy sewing.
Donna