Prism99

You can still adjust the bobbin tension. Your bobbin case has a hole in the finger. If you thread your bobbin thread through that finger before placing the case in the machine, that will tighten the bobbin tension slightly. If that is not enough, you can use a tiny screwdriver to tighten the screw on the bobbin case spring. Here is a link to a Threads tutorial on how to adjust that screw, but there are others on the net:
http://www.threadsmagazine.com/item/...nsion/page/all

It's a good idea to do the adjustment while the bobbin case is inside a baggie. I have loosened the screw so much it fell out! This screw is tiny and hard to find if not inside a baggie. It is generally recommended to tighten or loosen this screw in just quarter-turn increments, as it does not take much to change the tension. It's still a good idea to Google "how to adjust bobbin tension in a sewing machine" and read several tutorials before doing this yourself. Some people are so afraid they will not be able to get the bobbin tension back to where it was when they started, they buy an extra bobbin case. One is used for regular sewing and never gets its tension changed; the other is for experimentation with different threads. A dot of fingernail polish on the extra case lets you tell them apart easily.