1) Incorrect Needle Try a larger Needle. Needles are available in sizes from #000 to #8. The larger the number the bigger the Needle.
2) Needle Carrier Stud is Loose The Needle Carrier Assembly must be free to swing upon the Stud, but must not have any right to left lateral movement.
To adjust the Stud loosen the set screw, 4 9/32. Tighten the Needle Carrier Stud until it stops, then back it out 1/12 of a turn (30 degrees).
3) Check the Looper Setting Check that the Needle is not impacting or bending when it passes the Loopers.
4) Needle Carrier Stud Hole is Worn If a customer finds that he or she is continually readjusting the Needle Carrier Stud, it is a good indication that the Needle Carrier Stud hole is worn out. The machine should be shipped to the Merrow factory for service.