The best I have been able to determine is that all W&W D-9s will have a 7-digit serial number which will be between 2,200,000 & 3,000,000. If the 7-digit number begins with a 3 it will have been built by Singer. Some Singer built 9W machines have a number of less than 7-digits but also have a W in the number. There are no serial number records available for these machines. A general "Rule of Thumb" is to subtract 2,200,000 from the SN?of a W&W D-9 (Doesn't apply to Singer built ones). Divide the result by 75,000 & then add that answer to 1895. This should give you the year it was made within a range of ¡À 1 year.?
You can safely tell your Sister she has a W&W D-9 made within ¡À one year of 1900. It is not a Singer 9W1.?
