I have the same machine as you and was having the same issue. I cleaned everything several times and it still ate the fabric like it was starving. I had called to see what the cost would be on taking it in for maintenance and they wanted $90.00 for a $140 machine.
I realized I had been using alot of starch in the project I had been working on and wondered if it had built up on the feed dogs. I cleaned them with a q-tip and rubbing alcohol and that took care of the problem for me.