Quoted from Gatecrasher:Usually some of the counter-sunk holes in the playfield perimeter were not used from the factory. They used the staples instead. However, when you do a playfield swap you want to use all the screw holes which means you have to place the wooden side rails in place and drill the holes in the rails that weren't already there from the factory. It's pretty quick and easy to do.
Most of the time you can see where there were screws but they were removed. I think they screwed the rails down, stapled them and then removed some of the screws. Must have been a cost saving thing but really doesnt make sense to do all that over a few screws.
When I attach the rails I use all the screw holes but do not staple. On occasion I have even added a couple extras. Satin black should get you close to the original sheen. High gloss would look good too up against a clear coated playfield.