draw a happy face if the statement is true and if sad otherwise. 1. looping stitches is caused by improper threading and unbalanced upper and lower threading 2 seams pucker when the tension is too tight. 3 clogged thread in shuttle race will cause a machine to run noisily. 4 the needle thread breaks if there is insufficient oil and loose screw. 5. Stitches skip when there is too heavy pressure on the presser foot ​