Can you locate the Model No.?
Below is quoted from:
http://sewingmachinerepair.blogspot.com/
"On most Singer machines the model number will be a 2-4 digit number, often followed by a letter, and located immediately above or below the stitch length lever or dial on the right front vertical part of the machine. For example 401A, 2010, 185J, 201, 301, 221k, etc. Sometimes the number will be painted, or a decal, and on the older machines it may be on a tiny riveted plate."