Quoted from RyanClaytor:As you can see above, there's still a lot of dirt ground down in those cracks. Not a big deal for me, as I'll be sanding down the PF eventually, but I'd be curious to hear if anyone has alternate methods to get a deeper clean on a PF like this.
Mr. Clean Magic Eraser, aka MCME, aka melamine foam. It's a microporous abrasive that works like very fine sandpaper. Moisten it with 91% (or higher) rubbing alcohol. Great at removing ground-in dirt from those hairline cracks. Works a little too well, in fact, so be careful you're not removing more paint than dirt. Check the white eraser often, and stop when you see more paint than dirt. Or maybe stop when you see any paint. It's a fine line.
The MCME will wither away as you use it, leaving behind a white residue that's easily removed with alcohol on a rag. It leaves the cleaned surface a bit matte, which you can polish back to a shine with Novus 2. And if this was a playfield you're keeping original, I'd carnauba wax it after that since the MCME leaves the playing surface a bit vulnerable to future wear. But not in this case.
You're in the perfect position to learn good MCME cleaning technique. If you go too far and remove paint, you're sanding it down anyway.