1) Do not pull on the hoop in an attempt to wiggle threads free. This can damage your machine's hook assembly and/or cutter blade.
2) Take a sharp blade and cut loose any threads between the garment and needle plate (stitch plate) so the hoop is free.
Here are examples of tools that can be used:
Note: Do not snip at threads between the hook and needle plate. Just the external threads between the needle plate and the garment.
3) Once the hoop is free, remove the hoop.
4) Remove Needle Plate by removing the 2.5mm Allen screws that secure the needle plate. Here is a video with those instructions.
5) Clean any and all threads and dust from the bobbin area and inspect the knife.
6) Oil the hook since it is now all clean.
7) Reinstall needle plate taking care to make sure it is centered appropriately. See Steps 4 through 6 in the Technical Manual for step-by-step instructions.
8) Make sure the bobbin is re-installed.
9) Re-install garment and check top thread path.
10) Back up and proceed with sewing.