Ellietow,
To use the low shank Greist feet and attachments, you'll have to removed the adapter from the presser foot shaft on the new Kenmore. It will "most likely" be low shank machine. If not places like Sew-Classic have tutorials on how to tell what shank your machine has. Some of the newer machines that have the snap on feet don't have a thumb screw, they have a slotted screw. It's the same thread as a thumb screw so you can get one of those most anyplace.
Joe