Singer HD6620C Sewing Machine Instruction Manual (Model HD6620C) - 37 Pages. Lost your sewing machine's manual? We've got you covered! This instruction manual is the ultimate guide to unlock the full potential of your Singer HD6620C. No more confusion or frustration—just clear, concise instructions right at your fingertips. What's inside? Everything you need to know from setting up to mastering your sewing machine and all its features.