I stopped by a local antique store to see if they had any fountain pens, and I saw a 1930s sheaffer lever fill ( and a marble desk blotter) and was wondering 1. How likely is it that I will need to replace the ink sac (shopkeeper could not vouch for it), 2 how difficult is it to replace the ink sac, and 3, what does a pen of that sort go for? I did not pick these up yet, maybe next time I stop in. I could not get a picture, but the body had stripes going along it in a deep green, and the nib was only marked sheaffer, 3, and made in usa.