i baked open my light and one was leaky so there some little stain on the reflective part but im affraid to clean it

do somebody have a technique or i should let it like that ?

1998.5 Toreador Red/Midnight Blue Contour SVT - #5912/6535 - DOB - 05/11/1998 - RU-3530/CTA Intake Pipe MSDS Heaser/Y-Pipe Magnaflow #10435 9mm Ford racing SPEC Stage one/Spec Alum. Flywheel HERE