should have read the whole thread, I see :roll:
I have never heard of a plastic bobbin case, but my repairman did tell me that if my machine came with plastic, stay with plastic, and when the machine came with metal bobbins, stay with metal bobbins - - the reason being is the timing in the bobbin area is timed for those particular weights.
I'm glad you got your machine up and running again.
One time, I had a machine that I couldn't get to sewing. I kept it laying around for months and then finally I REALLY needed to sew with it. I tried one thing after another, INCLUDING trying to tear it apart, before I decided I should pull out the owners' manual and start from the very basics. I shouldn't tell y'all this, but it turned out that I had put the needle in backwards! I was home alone, but you can just imagine what kind of an idiot I told myself I am!
The real miracle is that I EVER figured out that the needle was backwards ... cannot tell you how I figured it out yet, but I did! so, I am sort of proud of myself, even if I am an idiot! LOL