I have a no. 12 van norman for sale and a customer asked what year it is. As per the normal information using the google on the internet machine there is a page that lists serial number info. It suggests the ser # should read 12-XXXX but also in the fine print it says there are some machines that were marked differently. My machine is marked with a 13XXX format . I did see some posts on a few sites that came up from the search saying they had similar numbers and their "books" recognized this number format. Does anyone have any information other than what is online?