In this video, we demonstrate how to check bobbin tension on the Toyota ESP 9100. We begin by removing the thread from the pigtail while leaving everything else in place. Then we pinch the thread between our fingers and perform a simple drop test, similar to using a yo-yo, by giving the wrist a firm snap and allowing the bobbin to drop.
When the tension is correct, we should see the bobbin drop about 4 to 6 inches. If the drop is longer, the bobbin tension needs to be tightened. If the drop is shorter, the tension needs to be loosened. To make the adjustment, we use the larger of the two screws on the tension arm. Only a very slight turn is needed, using either a fingernail or a small flathead screwdriver.
After making the adjustment, we pinch the thread again and repeat the drop test to confirm the result. Once the desired tension is achieved, we wrap the thread around the pigtail twice and insert it back into the machine. We also note that this check should be performed after about every 10 bobbin changes, since bobbin tension can gradually slip on the machine.
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