Hi All:
The once silver trim running around the windows on my bus has, over time, a= cquired a very dark black/brown color.  The discoloration occurs within= a plastic exterior and cannot be directly "touched" to try to cle= an, restore, etc.

Does anyone know

1. what causes this effect?
2. can it be directly restored somehow?
3. if it must be replaced, where would anyone suggest getting the material= and how difficult would you imagine the operation to be?
   

Thanks
--
Mark A. Williamson
Denver, CO
88 Wolfsburg Weekender (135K)