Never steel wool on anything, exception would be bare rusted metal. Chromed parts don't need it. You could try gentle polishing on the oval badge, I would not use anything more abrasive than liquid car polish, and test a tiny spot with cotton swab first. The whitish part is gritty, and lifts up grime. The numbers and decor on the stitch lenght lever back plate is usually delicate, I can't remember exactly how the paint is on the 401. I expect gold trims to be delciat, the beige paint is rather tough. If a badge is a bit dull, it might be wear, not grime, best leave it alone, just the gentlest of cleaning. Badges on some machines are soft metal and would scratch, the paint is often even softer, unlike the chromed parts.