I bought a project EM that had a missing insert. After checking the entire cabinet for the missing insert, I sourced a used one with similar yellowed color due to age. Sanded off the incorrect artwork and created a waterslide decal with the proper artwork in photoshop. Installed and touched up the keyline ink circle. Looked fine but not great.
Then I did a playfield teardown to tumble all the parts. That’s when I found the original missing insert stuck between the upper apron sandwich layers. I wasted many hours over 3 weeks.