Brother International SB3734T Operation Manual - Page 14

Chart of thread tension adjustment, One needle (Three thread) A: Reverse B: Surface C: Needle thread D: Upper looper thread E: Lower looper thread C A B Needle thread is loose. Tighten needle thread. (yellow or pink) C E A D B E A D B Needle thread is tight. Upper looper thread is tight. Lower looper thread is loose. Loosen needle thread. (yellow or pink) Loosen upper looper thread (green) Tighten lower looper thread (blue) E A D B E A D B 12 Upper looper thread is loose. Lower looper thread is tight. Upper looper thread is loose. Lower looper thread is loose. Tighten upper looper thread (green) Loosen lower looper thread (blue) Tighten upper looper thread (green) Tighten lower looper thread (blue) When you adjust the thread tension, do it in the following order: (1) Needle thread (2) Upper looper thread (3) Lower looper thread This is the easiest way to obtain the correct thread tension.