Let me begin by saying I am new to longarm quilting. I have had my Millie for 11 months and have been actually quilting on it for 6. I have not had a single problem until now. I follow all cleaning instructions, between quilts, as recommended by APQS, and have been using the same brand and weight of thread from superior (OMNI), and the same batting as all other quilts 80/20 Fairfield (frankly, I am afraid to change until I get better at understanding the machine and tension).
Now for my problem, the other day I noticed my tension was "randomly" off. I was using quilt path, as on several of my previous projects, and in small random spots my tension would be off. The front of the quilt looked fine, but the back looked like railroad tracks. It was not just before or after a stop or start. The machine would be quilting along fine and for a very short time the tension would get off and just as quickly it would be back to normal. I did check to see if it was in a certain spot on the pattern, but it was in random spots. I could not find anything consistent about the times it chose to be off.
I have no idea what to do and would appreciate any suggestions anyone might have. I always thought that if I had tension problems it would be throughout the entire quilt.