I wonder if sitting the thimble on the stove might be a way to remove the stuck marble? Hey, it works for installing valve guides.
Or, maybe just throw the whole thing in the privy...could be clue to why these show up in digs
From a 1920 publication:
https://books.google.com/books?id=EbJMAAAAYAAJ&pg=PA517&img=1&zoom=3&hl=en&sig=ACfU3U3XV_U11gthLAJMvHvmxjnWxf6upQ&ci=44%2C641%2C440%2C600&edge=0
Just a guess here but gold and sterling thimbles are quite soft and easily bent or squashed, rendering them unusable. Maybe storing with a marble inside prevented such damage.