The screw seems to be common in later Flues Models and NIDs. It is also found on a few Lefever Nitro Specials. A 1921 vintage Flues --
1941 vintage NID --
That serial number chronology is worth what you pay for it!! Doesn't have the Minier Models and shows the Lewis in the years of the Minier!! Much better one in the second edition of Walter's book, which is well worth the investment if one is going to play with Ithacas.