It's your grandfather's watch so, in my opinion, worth getting to a watch maker to see if they can get it serviced. I've got my grandpa's Sandoz watch and, although it was working, still got it serviced at great expense (about 5 x what the watch is worth) because it's my grandpa's watch and I want to wear a small piece of family history on my wrist. Watch is pretty much worthless to anyone other than me and my brother.