here is a pic
The 'frosted' or white areas on the inserts is the factory clearcoat (Diamond Plate) where it has seperated from the plastic lens. This can be 'improved' when its very minor - however I would place your playfield in the severe category. To rectify this, you need a sharp blade or hobby knife to score around the edges of all of the inserts. This will allow the delaminated clear coat (Diamond Plate) and associated insert artwork to fall away from the playfield. I would typically remove all of this, continue to clean and prep the playfield for its first clear coat. The plastic inserts need to be sanded to create a mechanical bond for the new clear. I would typcially sand the inserts with 180 grit. They will look dull until you apply the clear.
Once cleared, I would sand that down (400/600/800) so you have a seamless playfield again between the timber and plastic lens. Then you can continue to make repairs to the artwork, apply the insert decals and reclear the playfield, sand and repeat until you have a nice uniform finish.
I have recently completed this exact process on a rough CV so i ill try and post the process here as I think photos will explain it alot better.
Tim
HRP
