Are you even sure those parts ever went to your machine? I've looked at lots of pics and can't find where the plastic piece and spring would go. The part on the upper right doesn't even look like it goes to any sewing machine I've ever seen, and on the bottom is a c clip..they are pretty generic and used on a lot of things, but on sewing machines, they were used to hold the long stainless steel bars inside your machine, but it still doesn't look right to me, it looks too thick for a sewing machine c clip, but that just may be the pic.
Does the machine rotate with the hand wheel? Have you tried to sew with it?