Welcome to SBF looper. I also had no luck locating a manual for your machine but will take a guess that your machine is from 1965. The engine serial number starts with a 5 and that indicates it was made in 1965, 75 or 85. Being that it has the fancy engine cover that would probably be replaced with something cheaper in later years reinforces my 1965 guess. Whoever owned it looks to have done a pretty nice restoration.I still can't find the year or manuals. It has a Tecumseh H60-75106E with serial 5181 04182 It does not have a DOM.