Tension Troubleshooting Guide
A balanced stitch locks between the two fabric layers — where loops show up tells you which side to adjust.
| What you see | What's happening | Try adjusting |
|---|---|---|
| Loops on top of the fabric | Top tension too loose relative to bobbin | Increase top tension |
| Loops underneath the fabric | Top tension too tight relative to bobbin | Decrease top tension (or check bobbin tension) |
| Fabric puckering along the seam | Overall tension too tight for the fabric weight | Loosen top tension, or check bobbin winding |
| Stitches look fine on top, loose/loopy in a zigzag or decorative stitch | Bobbin tension too tight | Slightly loosen bobbin case tension screw |
The core diagnostic rule
A correctly balanced straight stitch interlocks the top and bobbin threads exactly in the middle of the fabric layers, invisible from either side. When you see loops, they appear on whichever side has the looser thread — top loops mean the top thread is too loose (or the bobbin thread is pulling too hard), and bottom loops mean the reverse.
Change one thing at a time
Adjust only the top tension dial first and test on a scrap, since that's the easiest and safest control to reset. Bobbin tension is a smaller, finer adjustment and easier to overcorrect — only touch the bobbin case screw if top tension adjustments alone don't fix the problem.
Rule out threading before touching any dial
A huge share of "tension problems" are actually threading problems: thread that's slipped out of a guide, a bobbin that's not seated correctly, or thread caught in the bobbin case incorrectly. Before adjusting any tension setting, unthread the machine completely, remove and reinsert the bobbin, and rethread the top from scratch with the presser foot raised.