you can buy size 21 needles at an industrial sewing machine supply place and your shaft will most likely accept the needle. The questions: Is there enough room for the needle and thread to pass through the hole? If the needle hits will it scar, burr or possibly bend your needle plate - then below that, nick the hook and causing burrs. If the thread rubs against the hole or a burr it WILL shred. I would test this out very slowly.