The presserfoot problem might be the bar itself. It could be gummed up.
Take the faceplate off and see what it looks like inside, it could very well be the pin or it could be seized up. If thats the case then good ole WD-40 can fix you right up. It might take a while but do not force anything. Then you can give the mechanics a good Kerosene bath trying not to get too much on the finish. Afterwards the Go Jo cleaning with cotton balls and Q-Tips, then hit it with the Scotts Liquid Gold in the pour bottle and its a new machine!
And if you want to clean the plated parts use SemiChrome or Mothers Mag Wheel Polish.
Billy