the row next to it was fine, but i could have inconsistent tightness of thread on the bobbin. Sometimes i go slow, other times hit the pedal to give it maximum beans
Tension issues also come up when the machine is overwhelmed by the materials. My poor little 1948 Singer was tough but multiple layers of canvas/leather quickly overwhelmed it, the Juki eats that shit right up.
Also check your needles are matched to the thread.
the row next to it was fine, but i could have inconsistent tightness of thread on the bobbin. Sometimes i go slow, other times hit the pedal to give it maximum beans