I have a Bernina Patchwork Edition. The problem I have had is that no matter how I adjust the tension, my bottom thread always seems loose. Have had it worked on and it works OK for a couple of days, then I am back to the same problem. You mention a timing problem. I have never heard this term and am not aware of what the symptoms consist of. I have occasionally (well, maybe a bit more) sewn over a pin or two. I have banished my Bernina from the sewing room and have been using my Singer Confidence Quilter on a steady basis. If any of you have had this stitch problem and it has been resolved, I would like to know the solution.
LeeJay