Several people have said that it will loosen up if I play it, so I'm trying that. I had another idea - I got my husband to open and close it a number of times. He agrees that it's much too stiff.

I think it was snapped shut, put in its case, put in a dry attic and forgotten for 40 or 50 years. We'll see what happens, but I'm not going to keep trying to play it when it's such an effort.