Adjusting the bobbin thread tension involves making slight adjustments to the bobbin case to balance it with the top thread. Here's how to do it:
The goal is to achieve a balance between the top and bottom thread tensions. According to the reference, you need to make slight adjustments to the bobbin case to achieve this balance. Move the screw on the bobbin case very slightly as you try to find that good balance. This is a delicate process, so make adjustments incrementally and test the stitch after each adjustment.
