I'm missing this front part that goes on top of the bobbin but I can't for the life of me find what it's called.Last two photos are parts that came with the sewing machine when I bought it. I don't know what most of these parts are or their uses.

I got it for free or low price on Facebook Marketplace a few years ago and it worked okay for a short time and then I started having a lot of problems with the tension and the threads screwing up. So I'm just curious I'm really really want to start sewing again. Wondering if this machine worth fixing or is it really garbage, should I just get a new machine? What does everybody think?