How can I fix Singer 8280?

I have Singer Model 8280. I just got it few months ago. On the beginning I didn't have any problems. Everything started when the needle broke. I changed for a new one. Than thread stuck in the bobbin. I had to take the bobbin apart because I couldn't take the thread out. And now I have a problem with putting it back together. I have three pieces-bobbin, round metal piece and the one that bobbin goes on. It seems obvious what goes where but when I put it together the thread stucks in the bobbin again. What am I doing wrong?