Or, just use a piece of MDF the correct size and paint it white.
I repaint the inserts on games I restore. It's not tough at all, take a socket the right size to bridge the front of the socket, and carefully tap them all out. Clean the light board with your favorite cleaner, sand the back to get the dirt off of it, then mask the back and spraypaint it.
Wash the harness, let it dry, reassemble.