*sigh* We had this discussion on the old board, because the adjustable drain plug wrench also goes through those handle style changes, but it went poof with the board...
The ring style is after 1946, but a 1 date code would make it 1941, could the 1 be a 7? (1947) that is the last year for the digit codes...and would make sense for the handle style...
(The latest patent is 1935, so that doesn't help much)