I just sewed a block together, being careful not to pull or stretch the material and it came out with little puckers anyway. It really ticked me off because now I have to make another block. I clipped a couple of threads to see if it would release the tention, but it wasn't enough. Cause---the bobbin thread was stronger than the top thread and was pulling on the weaker thread. I changed to lighter weight thread and no puckers.