In this video, we show how to properly clean the bobbin case and reset the tension afterward. We begin by loosening the large recessed adjustment screw just enough to see daylight under the spring. Using a small screwdriver, we make only a slight adjustment, then gently clean underneath the spring with either the toothbrush from the tool kit or the corner of a paper business card. As we clean, we are careful not to bend the spring in any way.
Once the area is clean, we reset the bobbin tension using a brand new bobbin. We make sure the bobbin is forming a 9, never a P, meaning the thread comes off the top to the right. We do not rely on the printed writing on the bobbin, since the print orientation can vary. Looking at the back of the bobbin case with the pigtail facing straight up, we place the bobbin into the case, guide the thread into the slot, and then slide it up underneath the spring.
We then rotate the bobbin case slightly so we can see the adjustment screw and tighten it to set the tension, checking it a couple of times as we go. After that, we perform the drop test. For this test, we do not wrap the pigtail. The pigtail is wrapped only right before installing the bobbin case into the embroidery machine. To prepare it for installation, we wrap the pigtail, pull the thread straight down the face of the bobbin case, and snap the thread tail so that 2 to 3 inches remain, which is the correct length for placing it into the machine.
To verify the bobbin case tension after cleaning, GPI offers a dedicated tension gauge.