I have a Brother Innovis 4000D. It was making that type sound. The first time it turned out to be a couple of itty, bitty threads caught up in the bobbin area & in the automatic threading mechanism. The next time, I had to buy a new bobbin case. It was catching the thread & making a huge birds nest. When the first problem occurred, I had not taken the machine in to be oiled for several years. The tech found the thread when he was servicing the machine. If you haven't had it in for a tuneup, now may be the time. FYI...There are no areas that show in the manual for a user to oil. There is a small screw on the back of the machine, right above the pressure foot. It allows you to take the cover off the head. I probably could have found the upper thread, but I definitely would not have known how to make the other adjustments to the unit. It really needed to go see the tech. lol
Should have mentioned that the thread cutting mechanism makes a grinding sound all the time.
Last edited by Barb in Louisiana; 08-25-2012 at 05:21 AM.