Bernette 75 won't Zig-Zag

Does it straight stitch with a zig zag foot? Go back into the menu and clear everything then go to straight stitch, then press the little buttons beside the Zig Zag dial to position the needle left or right

Do you have it on zig zag or maybe it is in one of the hem stitches. Make sure you have not selected a special stitch. Sometimes with a small width setting it looks like no zig zag, then when you increase the length you see it is not.

Have you rethreaded the machine, making sure to get the thread between the tension discs?

have you tried changing the needle?
have you tried adjusting the top tension?

it's very possible that the machine is slightly out of time & needs to be service at a sewing machine shop
is the fabric & thread & needle compatable with each other?
did you use every thread guide when threading the machine?
is the bobbin in correctly?
is the bobbin warped?

Check that you have got the thread correctly routed on the bobbin case and that there is noticeable 'drag' on the thread when you pull the thread out of the bobbin, in its case. If there's little or no drag, it is likely that the bobbin tension needs increasing. I'm assuming you've set the top tension to thered line. A good check is to load two colours of the same thread type top-and-bottom - when sewing on wide zig-zag, the top thread colour should be the only one seen on the top of the material and the bottom colour should be mostly seen on the bottom ... it's OK to have just a spot of the top colour showing on the underside on wide zig-zag/satin stitch.

If the bobbin thread is coming up to the top, then the thread is not under tension correctly. I think that this is a top loading bobbin so the bobbin will go into the bobbin holder, then you pull the thread back and press it into a tension device - should hear it click into tension. Now pull the thread back towards you and it should not come out of the tension. The bobbin should turn anticlockwise as the thread is pulled from it.

These bobbin holders usually will have a small adjustment dial on them and it should have the standard setting marked in red. It is very unusual that you would need to change this but check that it hasn't been messed with perhaps. If you have the machine manual check where they say the dial should be set. More likely that the thread is just not into tension fully or at all.

The manual may give you other troubleshooting tips too.

A good resouce is www.sewing.about.com for general machine tips, cleaning and threading issues.

Hope this helps.

When you thread the top thread, ALWAYS RAISE the presser foot so the thread will seat completely in the tension disk. If this doesn't improve the stitch, try tightening the top tension. If it is too loose, the bobbin thread will lay on the surface of the fabric. When the top tension is tightened, it will pull the bobbin thread up into the fabric.

If your stitches do not look good on the top side you have a problem with the bottom thread. make sure you have the correct bottom tension: Is the thread under the bobbin tension plate and when you hold the bobbin and case lightly in your hand the tension should be set in a way that there is little resistance , yet still some, when you pull the thread. After you set your bobbin tension, you may have to adjust your top tension to balance. Also make sure the thread comes off of your bobbin the way your manual tells you, clock or counter clock wise.
Make sure your bobbin (plastic) is not sooooo old, buy a new one.

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.