I just bought this machine at an estate sale for $10, the best I can read the number it is 2547784, I looked it up on the Ismacs site, it says no letter prefix was before 1900, did they have electric machines this far back? It sews, seems a loud, got it oiled up. The case it was in really smelled bad and looked even worse, I had an extra case that I was able to put it in. I'm not sure how the tension works, it has the screw type, I had to use plyers to back the tension off. It has the 66 drop in bobbin case. Anybody familiar with the brown crinkle machines?