Practical guide · sewing machine tension problems
Sewing Machine Tension Problems: A Practical Fixing Order
Diagnose loops, puckering and thread imbalance without blindly turning every tension control.
Start with the decision
Start by returning to a known setup. Raise the presser foot and completely rethread the upper path so the thread can enter the tension discs; remove and reinstall the bobbin in the direction shown in the machine manual. Fit a fresh, correct needle and test with ordinary thread on a folded scrap of the same fabric. Photograph the original settings before changing anything.
What changes the answer
Loops underneath often point to missed upper threading, while thread showing heavily on top can involve the bobbin path, but symptoms overlap. Needle damage, lint, incompatible thread, unstable fabric, embroidery stabilizer and a design that is too dense can all imitate a tension fault. Clean only the areas and by the method approved in the manual, then test one change at a time from the default upper-tension baseline.
A sensible next step
Do not start by turning the bobbin-case screw: small changes are difficult to reverse and many drop-in systems are not intended for routine user adjustment. If correct threading, a fresh needle, suitable thread and a clean bobbin area do not restore a balanced test seam, stop using the machine and arrange qualified service—especially if there is noise, resistance, needle contact or repeated thread damage.