I am having troubles with the decorative stitches bought used

The stitch Width selection regulates straight-stitch or zig-zag width. Needle position does not determine straight or zig-zag. Needle position just determines whether the needle's home position is center, left, or right. Needle position can be used with straight or zig-zag stitching.

could you explain more about what the machine zig zag stitch is doing or not doing?

In most cases Laurie, with decorative stitches selected some machines can't sew in reverse. Your stitch length is too long or too short to make the decorative stitches sew correctly. So many things could be wrong. I'd need more info to get you going again.

Cheers,
Kelly
San Diego, CA
Embroidery Services

Hi Susie,

I can't tell whether you mean straight stitching and then turning your work 180 degrees to stitch atop the straight stitches in zig-zag, or continuing around the corner of your straight stitched side using zig-zag. But you can do either. You can mix up straight and zig-zag stitching at will.

Just ease up to a stop, ensuring the needle is positioned down inside the work when you stop.
Lift the foot.
Adjust to your desired stitch setting.
Lower the foot.
Turn the wheel toward you manually to ensure the stitches will be placed where you want them, and
Slowly engage the power again (via foot or thigh lever).

Hope this helps.

it sounds like the decorative cam or gear is damaged.. it would be a good idea to have the machine checked

Sounds like the pattern selector is bound up. Make sure your zig zag is set to zero when changing patterns. That may help.

You have the machine set for blind hem stitching. Change the stitch selector to stretch stitch, which is a single, in line stitching zig zag stitch.

Cheers,
Embroidery Services
San Diego, CA

First, make sure you select the straight stitch setting on the round dial. It is the one that has the dashed lines, looking like the stitch itself. Then, you may also want to be sure that the stitch WIDTH (dial with the picture that looks like a straight line gradually turning into a zig-zag) to the lowest setting, which is generally 0. With some machines, even after selecting a straight stitch setting, moving the stitch width can change needle position. Sometimes it will initiate the zig zag, other times it will move needle position left to right. Does that fix it?

make sure the pattern selector is set for straight stitch first. If it is set correct then the machine may be "stuck" is zig zag mode. May need to be de greased and then re lubricated.

Because it is almost a straight stitch but the needle continues to move in a zig zag fashion is reason to believe it is in a long stitch. By changing the number of stitches per inch there will be a very noticeable looking zig zag stitch.