Small Scale Military Headquarters

Hello guys! Okay? Late last year I managed to buy a RAAF F-18 BBI ELITE FORCE Squadron 75, it is used and when I realized I had received yellowish parts, the seller made ​​it clear to me before I sell it I believe is the time even so it did not leave me frustrated because it is rare and bring it to Brazil was too much risk.
I need to know if anyone knows any product that I can spend it to get these yellowish stains without damaging it.

Thank you!

It depends on what has caused the yellow stains. is it coffee or paint spilled on the model? Is it yellowing from direct sunlight? Is it yellowing from cigarette smoke? Always try soap and water first.

I do not know friend, I see that the left side is yellow, I think it is exposure to sunlight or wear can be, but does not come out with soap and just wanted to know if there is a reliable product that I can run and not damage model.