For a SINGER Heavy Duty 4423, the manual lists the SINGER 2045 semi-ball-point needle for jersey and other knits, including interlock, tricot, and elastic fabrics. It gives upper-thread tension 4 as a basic reference, but it does not prescribe a jersey-specific dial number. The same manual says no single tension setting suits every stitch, thread, or fabric.
The needle/fabric chart groups lightweight fabrics, including jerseys and cotton knits, with sizes 9–11 (70–80). Treat that as a broad manual example, not one required size for every jersey. The manual says to match needle size to thread size and fabric weight; the actual knit construction, layers, and thread still matter.
Test the complete jersey setup#
Check that the machine is the 4423 and that its manual matches your model revision. Select a needle type and size within the manual’s limits, thread the machine as directed, and sew a sample using the same jersey, layers, thread, and stitch as the project. Inspect both sides for skipped stitches, loops, puckering, or thread damage. If the stitch is unbalanced, recheck the full thread path and bobbin before making a small tension change and sewing another sample.
Use 4 only as the manual’s basic reference, not as a guaranteed jersey setting. Do not transfer the 4423 guidance to another SINGER Heavy Duty model or regional variant. For general fabric-first needle selection, see the needle type guide; for the thread-path checks, see tension troubleshooting.