If the tensioner is on the front face plate of your machine, I think you probably have a Japanese clone of a Singer Model 15....You are LUCKY!! They were actually made better than the Singer model 15, and a lot of people think that is one of the best machines Singer ever made.
You can drop the feed dogs by a little mechanism under the front of the machine so you can free motion quilting on this machine. Get yourself a Singer 15 manual (for free) off the internet, and it will also be accurate for the one you have.