What should I do if the upper thread tension is too tight and loops appear on the surface of the fabric?
Reduce the tension by turning the upper tension control dial to a lower number. If the bobbin thread was incorrectly threaded, the upper thread may also appear too tight, so you should rethread the bobbin thread following the lower threading instructions. (Page 1)
From the official Brother XG4099-001 Computerized Sewing Machine manual, page 1
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