Janey,
The feed dogs are not jammed up, they just are set to far to the rear. The teeth hit the back of the slot of the needle plate and part of the feed dog under the needle plate is hitting the body of the machine. Has actualy deformed the corner a bit.
I've studied the feed dog adjustment under the needle plate and from what I can see all that does is raise and lower them. I need to find the adjustment to move them forward and backwards.
Joe