Oh, I HATE when stuff like that happens! Totally messes with the plan. I messed up the timing when I hit a needle once, and I have run short on backing also. I had a take a quilt off the frame and match the big dot fabric design after the lady brought me more fabric. The good news is, the quilt got done. I hope your machine is working OK now. They don't tell you that you should be a mechanic to run a long arm!