Dear Mr. Myhre,
Thank you for posting your request on History Hub!
We searched the National Archives Catalog and located 10 file units & 19 items in various record groups that pertain to the Singer Manufacturing Company during the 1960s. All of these records have been digitized and are available using the Catalog.
We also located the series American Unofficial Collection of World War I Photographs, 1917 - 1918 in the Records of the War Department General and Special Staffs (Record Group 165) that includes a file unit titled Industries of War - Manufacturing Sewing Machines. The contents of the file unit have been digitized and are available using the Catalog
In addition, according to the following webpage titled Singer Factories - Bridgeport, CT, Singer bought its competitor Wheeler and Wilson Manufacturing Co. located in Bridgeport, CT. All machines made at this factory had a W-serial number.
Next, we located a website, ISMACS International, the International Sewing Machine Collectors’ Society and located numerous categories for the Singer Sewing Machine Company including manuals, industrial models, household models, as well as the company’s history.
Finally, we located the website of the Hagley Museum & Library that has custody of a collection titled Singer Company records, 1851-1990 which may include the records you seek. The Singer Manufacturing Company was renamed the Bicoastal Corporation in 1989.
We hope this is helpful. Best of luck in your research!