WOW - That came up VERY nice ! How did you get that playfield to SHINE ?
Forgot to answer earlier. Multiple steps:
1) magic eraser - a must-have for any machine as dirty as this. I use it with a degreaser and it removes 99.9% of the ground in dirt on the playfield.
2) clean the playfield really well. Naptha or any good cleaner that doesn't leave residue should work well.
3) 3m rubbing compound - the same stuff you use on cars since the coating on pins is basically the same (diamond plate.) I use a 15k rpm chorded drill and buffing pads from harbor freight. Get the pad damp and use little blobs of compound and buff the playfield until you start seeing a mild shine. Usually two or three applications.
4) clean the playfield really well again.
5) Use a paste wax - turtle wax or meguires works really well. apply wax, let sit, use same drill with a buffing pad. I do this twice.
6) one more paste wax application and hand rub.
shiny playfield.