I bought a small tub of Quick-Glo for my 201, I knew it would do a good job on chromed bicycle parts too. It cleans and polishes up needle and presser bar like new. I think these are forged steel, at least steel with out chrome or nickle and they can be tough to shine up. The faceplate and chromed lids shines up nicely too. For this job it turn out better than Autosol, (not to degrade Autosol in any way, it has its' advantages). There are lots of polishes, I'm sure others are just as effective.
I don't know how to describe it really, but I take a rag or tear a strip of a cloth and when I rub it against the needle bar half a century of grime and dried up oil comes off in just a few seconds. It's made for chromed parts on cars, but other metals too. It removes rust and grime with ease. If you have something that already does this it's good enough, but if you happen to struggle to get these part clean looking I'm just saying there are better polishes available.