Camaro Heater Control Lens Resto

[169yenko]

My heater control lens has the edges of the black back ground turned brown. I have never taken one of these off, but noticed in looking at a reproduction lens that the back ground appears to be nothing more than a black peice of paper. Is there something someone has done to refurbish the original lens back ground? Mine is in very good condition other than the edges are brown in a few spots. Is the brown basically the edge/back of some original paper deal? Thanks