The Stylist 513 was made by the Singer Company in the early 1970s. The Stylist zigzag sewing machine featured all the basic capabilities, such as straight and zigzag stitching, and also had a stitch regulator dial for adjusting stitches and tension. The bobbins used in the machine were clear and the selling point on those were that you could see the thread amount before sewing. Troubleshooting this machine involves replacing bent needles, checking the upper thread and ensuring the bobbin is properly inserted.
Turn off the sewing machine. Raise the needle bar to its highest position, by turning the handwheel counter clockwise.
Loosen and remove the old needle, by turning the needle clamp. Grasp the handle and turn toward you, then pull down when the needle is loose.
Insert the new needle with the flat side pointing to the back, and push it up as far as it will go. Tighten the needle-clamp down to secure the needle.
Turn off the sewing machine. Turn the handwheel toward you to raise the needle to its highest position.
Place the spool of cotton on the spool pin on top of the felt, and lead the end of the thread through the tension disk slot. Bring the thread down through the needle thread tension dial and back up to the take-up lever.
Follow the path to the needle clamp hook, and slip the end of the thread inside. Thread the needle by going front to back. Pull the thread out about four inches toward the back of the machine.
Raise the pressor foot to the highest position. Open the slide plate toward you, using a little pressure, to remove the needle plate.
Remove the bobbin. Turn the bobbin case until it releases, then lift it out. Inspect the bobbin case, and replace if worn or damaged.
Place a new bobbin case in the compartment, and turn until it locks into place. Insert a bobbin in the bobbin case. Replace the needle plate by sliding until it clicks into place.