On Model #535 FA The feed dogs do not come up high enough to advance the fabric forward. Is there an adjustment to raise the feed dogs ? ( Necchi sewing machine )

On the top of your machine at the far left, there is a round knob (looks kind of like a nut) with round metal post sticking up in the center. This is your presser foot pressure button. To increase the pressure, push the center post down. Generally, all the way down is for fine, thin fabrics that are harder to feed. You can set the degree of pressure to coincide with the type of fabric you are stitching. CAUTION--this is spring loaded, so your machine should not be put away with the post pressed down. To release the post, gently press down on the outer ring and the center post should pop up. If your machine has been stored with the button depressed and it no longer provides pressure, then the spring is probably compressed and needs to be replaced. (Or, you can try removing the spring and manually stretching it, BUT THAT IS A RISK AND MAY HAVE NEGATIVE CONSEQUENCES. However, if you need to replace the spring, you can give it a try anyway... I've done it on my old Necchi and it helped.)

The other possibility is that the feed dogs have been worn down (one reason why a sewing machine should not be run with the presser foot directly on the feed dogs--should always have fabric between them.) The feed dogs are sharp when they come from the factory but they do wear down with use. You may need to have a technician replace the feed dogs for you. You shouldn't do it yourself as they need to be installed properly.

If you change the number of your stitch length it will automatically adjust the feed dogs. If it is still a problem then you will need it adjusted. Insure that your pressure foot is placing enough pressure that causes the feed dogs to pull the material forward. To adjust the feed dogs there are different ways to be adjusted. I wouldn't suggest you try to adjust the height of the feed dogs.