Thread breakage or shredding can be a frustrating problem when using a sewing or embroidery machine. Here are some steps you can take to troubleshoot and fix the issue in your Brother SE600 Sewing and Embroidery Machine:

1. Check the needle: Make sure you are using the correct needle size and type for your fabric. A worn or bent needle can cause thread breakage or shredding.
2. Check the thread: Ensure that you are using high-quality thread that is suitable for your project. Poor quality or old thread can break easily. Also, check that the thread is properly threaded through the machine and tension discs.
3. Check the tension: Improper thread tension can cause thread breakage or shredding. Adjust the upper thread tension as needed. It may also help to adjust the bobbin tension.
4. Check the machine and bobbin case: Check for any burrs or rough spots on the machine or bobbin case that may be causing the thread to break. Clean the machine and bobbin case regularly to ensure smooth operation.
5. Check the fabric: Thick or heavy fabrics may require a larger needle or a slower sewing speed. Thin or delicate fabrics may require a smaller needle or a stabilizer.

By following these steps, you should be able to identify and fix the issue of thread breakage or shredding in your Brother SE600 Sewing and Embroidery Machine.