I have owned the Smarter C1100 for about a month and I had the low bobbin sensor go off, but it wouldn't do it for the tech. What I found, and read this by someone on some forum too, is that, I sit by my sliding door and if a really direct sunlight comes in, the sensor goes off and won't let me sew. I tested it a few times by partially lowering the blinds, and poof, the sensor didn't come on. It was that simple. I have the quilter's toolbox with the plexiglass clear table, so for some reason too much light must hit the sensor. I still can sew with plenty of good light, so I am happy.
If your having trouble with your thread cutter leaving thread springing up too much, like within a half inch of the needle hole or up into the take lever area, try feeding your thread from a separate spool holder for smoother feeding off of the spool. I was having trouble with cotton thread. I have lot of Superior Masterpiece cotton thread on 3000 yd spools with a wide (1 inch) center and they are about 4 inches tall. I realized the thread was kind of whipping awkwardly off of them.
With those two things combined, it made the tension too tight intermittently, so when I would auto cut, I believe that little bit of spring caused the thread to fly up. The cutter works works fine with regular small spools and poly type embroidery thread on the regular spool holder. So, I'm just using my side spool holder for all of that Masterpiece I own.
Now, I think my Smarter is great machine, the pfaff feet are so nice, with dual feed, and it just glides over thick quilting seams. [ATTACH=CONFIG]327822[/ATTACH][ATTACH=CONFIG]327823[/ATTACH] Just wanted to post this in case it helps anyone.