It might be worth stripping out and re-lining; not as hard as you might think. I obtained a nice leather on oak case and was faced with the same problem. I actually enjoyed doing it and have since done a few more. I have a similar problem with a leather and sheepskin lined gun sleeve at the moment. I picked it up as a second hand bargin but the previous owner smoked. I keep hanging it inside out in the sunshine to try to get rid of the stench. Not enough sunny days in England this year and it is taking some deodourising. If that was the inside of his gun sleeve I hate to think what the inside of his lungs were like. Lagopus......
