Also interested. I have a Stern Seawitch & am about to start cleaning up the playfield too.

Well apparently hi percentage alcohol on a Magic Eraser takes off some, if not all, original clear. So unless you're planning on clearing, maybe shouldn't be that aggressive.

There is a good thread

https://pinside.com/pinball/forum/topic/cleaning-and-waxing-pinball-machines-vids-guide

where a lot of options are covered. I use Mother's Mag polish on vintage fields. NOVUS just doesn't cut it in my experience.

Try not to use anything abrasive unless your intent is to remove ball swirls, touch up and clear the playfield. These games got played to death and there's little, if any clearcoat protecting the playfield. A mild cleaner and a good wax are all you need for normal cleaning and play.