Wurlitzer 1015 selector question

Hi
I have a question regarding the selecter assembly on an original 1015. I don't have a manual yet, one is on the way, so I'm not sure what they are called.
If you open the door and look at the 4 selecters, on the left of each one is a (what used to be clear, I think) plastic or phenolic board on stand offs. They look like they don't do anything, other than strengthen the selecter. They have aged to the point, they are deforming the selecter assembly themselves.
My question is about reproductions. I called Victory Glass. They said to just remove them, they are not needed.
I would like to make reproductions to keep it original.
What is the "best" material to use. I thought about using clear plexiglass. Or maybe even a electrical insulator type board.
And what thickness ? Has anyone performed such an operation ? Or just leave them off ?

Thanks to all...
Tony