Brother Z-8550B Instruction Manual page 99

Check the upper thread tension.
2
Lower the presser foot.
3
Adjust by turning the tension
nut (2).
4
After adjusting the upper
thread tension, pull the upper
thread in the direction of the
arrow and check that the rotary
disc (3) turns together with the
upper thread.
If it does not turn, tighten the
pre-tension (4).
If the tension of the pre-tension (4) is too weak the thread will slip and the rotary disc (3) will not rotate. The
pre-tension (4) should be adjusted to as weak a tension as possible while still allowing the rotary disc (3) to
rotate smoothly.
Related Information
• Adjusting the upper thread trailing length after thread trimming on page 122
86