I have had my machine for almost 1 1/2 years. It has always run very smoothly and I clean the bobbin case every time I change the bobbin. I've always used Coats & Clark specialty threads. The past couple of weeks it started making these grinding noises and the upper thread kept breaking. I asked on here about taking a machine in and a couple of people suggested trying a different thread. So I went to JoAnn's and bought some Sulky thread. Holy moly!! It's working fine! What's the deal? Why all of a sudden would I need to use a different brand of thread?

Are you using the correct needle for the type of thread?

I've been quilting so I'm using quilting thread.

And what size needle? Quilting thread is a heavy thread. If you're not using the appropriate needle, I would expect the thread to break.

If the machine was making a grinding noise, it could be due to something else other than thread. It may not be such a bad idea to have it checked, cleaned, etc.

If it was grinding, that sound might have come from somewhere inside your sewing machine. DH cleaned my HQ16 after 2 years of medium use - about 20 quilts. It was immaculate inside - EXCEPT for one piece of thread that was wedged into the mechanism that raises the needle up and down. The HQ16 was running fine, but who knows for how long that would have been the case?

You can test whether it was the C&C thread or not by trying C&C again.

However, if your machine is an expensive one, I think I'd get it serviced, just in case.

I agree with quilttiger - anytime my machine makes suspicious noises I make sure to clean it, change needles, rethread, pull out the bobbin and put it back in. If noises continue take it to the machine doc.

Is it possible you're using the hand quilting thread? It has a finish that isn't good for machine quilting.

I don't know why but for some reason I keep thinking there is something stuck in the area of the take up lever.