When I went to class the instructor said where the right needle is and where the blade cuts was 1/4" seam. Would the left needle be the 1/2" seam allowance ?? The seam allowance markings are not flat on the machine like a sewing machine. How do you mark your seam allowance. How do you do your seam allowance?? The serger I bought is a Kenmore Overload 2/3/4D Model 385.81595 Serger is equal to Janome 644D. Thank you B.