I would take it in and have it serviced.

I don't know why my friends bernina dislikes many types of thread mine same make and model loves any I use. Why?
I think it is like cars Friday cars have faults and some sewing machines have a will of their own .somebody on her has a quote never tell a sewing machine you are in a hurry. It's true when rushing or thinking that bobbin will just do this if the machine hears oh no it want.

My machine seized up once, all for a few drops of oil up the top of the needle shaft, it made noises at first too. We're not told to oil, or where to oil when we buy them. I does seem as if there could be a bit of thread caught somewhere as well.

I agree with Dunster, are you using quilting thread meant to be used for hand quilting only. It has a wax finish on it that is not good for the machine.

QUOTE-I have noticed that the quality of some lower priced threads seems to be getting worse. I don't know if that was your problem but I really like the Aurifil now (even if it is pricey.-QUOTE

Just saying, I've had good experiences with connecting threads thread as well.

I don't know a lot about different machines and at times mine is a mystery, but mine makes grinding noises when it has to do with up and down of the needle shaft lever.

I've had some funny noises come from my macine, too!

I had better go out and find some oil for my machine... That and get another can of "air" to blow out my bobbin housing! Thanks for the tips! :)

Susan, air is not usually recommended for DSM's because it blows the particles back into the machine.

If your machine's manual shows you where to oil and lubricate your machine, then it is relatively easy to do, and you don't really need to take it in for service. Be sure and use a good sewing machine oil (Singer is good, or there may have been some included when you purchased the machine). If it calls for a lubricant, do not use oil. Singer lubricant comes in a tube. Clean out all the lint and threads that you see, especially around the bobbin area, which you said you do. Many times, when thread starts breaking, it is because the machine was threaded incorrectly. You didn't say whether you had changed the thread before it started breaking, but I suggest that you try again with your original thread and just rethread the machine.

I don't use Coats and Clark anymore. Their quality is way diwn. I had trouble with thread breaking.

Yes Dunster is correct - you really need to watch and make sure that you DO NOT USE hand quilting thread in a machine.