Machine is "gathering" stitches.
 

I am not sure why my Bernina 440 has started to "gather" my stitches. I just finished quilting a quilt using both FMQ and straight line with my walking foot, and had no problems. I went back to my normal setting of 4 on my upper tension, cleaned out the fuzz under the stitching plate, am using Aurifil in top and bobbin with a 90 needle (didn't change the needle from quilting). I was chain piecing today and the squares started gathering. My setting is at 2.4 (factory setting) and I don't know what to do to fix this. The internet was no help with this problem. Any ideas?

I would try changing the needle. Check to see if the top thread path is clear. I had my thread get wound around the spool peg.

I would guess your thread is catching on something on your machine. My Brother feeds off sideways, and if I am using thread that has a small nick in the edge of the spool for anchoring the thread after you have finished using it, the thread will catch on it and gather and/or break. I use mostly cones...some only 1100 meters and some 5000 meters and because of this I now use a free standing or machine mounted thread holder and no longer have the problem.

your tension

I think this was pretty much it. I did change my needle to an 80, rethreaded, but noticed that while I thought I had changed my tension from my quilting project, I had not - I did that and no more problems. Thanks for your replies.