One more comment. As I've been looking at all the beautiful machines I noticed that many of them have the presser foot down on the feed dogs. In many of the owners manuals I have there is a caution to not store the machines with the presser foot down on the feed dogs or to run the machine with the presser foot down and no material under the foot.
To keep the metal to metal contact to a bare minimum I make a little pad out of denim to put between the foot and feed dogs. You can see this pad in the pic above.
This is just a suggestion as I've replaced many presser feet that are badly scored by running on the dogs with nothing between them.
Joe