[QUOTE=thepolyparrot;4850288]
One thing you might want to try is dripping a couple of drops of Tri-Flow or sewing machine oil down into the top of the motor at the base of the vertical gear, in the seam. Then run your machine as fast as it will go for five minutes. This may loosen up any old dried crud that might be making your motor sluggish.
If that works, save some motor oil and drip one or two drops of motor oil into that seam. It will work much more slowly and dry very slowly, giving you some extra life in the bearings.
I would try this first before sending the motor out for repair. If you go to the Yahoo Vintage Singers Group, you can get a lot of info on vintage machines...you have to join the group.