I originally posted this in the Pelikan forum, but I am hoping I might get a few more suggestions. I have a Pelikan 100 that I acquired about a year and a half ago from a dealer in Madrid (1938 vintage). I tried it out in the shop and observed it being filled. It has continued to work nicely until last week. Suddenly (drum roll?) I couldn't turn the piston. Totally stuck. I removed the nib and flushed the barrel but no change. Is there anything further I can do or does it have to go out for repair? Thanks for any suggestions.