Sewing help?

I'm new to sewing, pretty much just like a 5th grade after school sewing class and home ec for my experience. So now I really want to learn how to sew well, but my sewing machine has something wrong with it. I'm pretty much dirt poor so I can't take it to get fixed. It is a few years old but it hasn't been used much so it should work all right, right? Anyway my problem seems to be in the bobbin area somewhere. So like the bobbin case (http://www.strima.com/image/133489/B1810-761-0A0+-Bobbin-case-for-Juki-LBH-761.jpg) theres a tab thingy in the front you pull out when you click it in the machine so while Im sewing I think it flips out because its really loose and I think it catches the thread. Can I get a new one for cheap and how do I know if it will fit my machine? Anyway I BELIEVE this is my problem because I tried taping the tab down with a bit of tape and it worked well until the tape unstuck and jammed my machine. Any help much appreciated